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hi this is my quest on Medibank dot org

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and we're having a look at the meta

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bunker refraction simulator I wrote this

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refraction simulator over the last who

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would have know several months based on

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a view of Toronto this is Toronto here

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and this is the CN Tower and this white

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thing here next to it is the Rogers

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Center and this view is from Fort

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Niagara which is across the lake on the

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other side of the lake ontario and from

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that site from that position

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theoretically you shouldn't be able to

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see the Rogers Center cause it should be

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hidden behind the curve but you can see

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it because of the refraction lifting it

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up beyond the curve and you know this

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confuses people so I wrote this

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refraction and simulated to explain

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what's going on enough to demonstrate

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what's going on first of all let me just

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show you real quick watch this is

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beautiful

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there's a checkbox over here on the left

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where you can turn refraction off so if

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I turn it off this is what you would

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expect to see if there was no

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atmospheric refraction it did this all

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these buildings down here a hidden but

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when there is refraction it pops into

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view now of course refraction isn't a

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constant so I had to make it editable

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and over here on the upper left hand

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side is the temperature profile the

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temperature on celcius is along the

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bottom and the height above the water

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level in feet is on the left I'm kind of

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mixing my metric and imperial units and

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this is a curve editor and this curve

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represents what the temperature is at a

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particular altitude say at 60 feet here

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it's 15 and a half degrees so I can grab

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that and I can move it around and you

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can see this has a quite dramatic effect

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on what you actually see this curve

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editor you control by moving these

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points around you can change the shape

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of the curve with the green and you can

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change the actual data points by moving

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the black ones around you can add new

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points if you want to make the more

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complicated curve by just clicking in

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any empty space and it will make new

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points you can delete points by left

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clicking and that will remove a point so

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you can create all kinds of interest

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effects that are things that you can see

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in real life you can see for example you

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can see big compression near the horizon

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here and you can see the Roger Center

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being lifted up if you have the water

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temperature of the lower down

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temperature a lot hotter than the upper

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temperature you will create a kind of

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mirror eyes effects where you get this

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this mirroring which kind of looks like

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what you see sometimes on a hot road

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when the road is very hot compared to

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the air you get this reflection this

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kind of total reflection a reflection

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from refraction so you can mess around

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with this temperature curve and see the

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various effects now of course it would

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be a bit boring if we just did Toronto

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so I made it very very configurable and

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you can actually look at lots of

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different places in the world and lots

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of different situations you can even set

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up your own so that's just go for your

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your food let's go through a few things

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right now I'm gonna look at the controls

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over here and I'm just going to reset

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this we click on preset link it will

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load the last that's preset that you had

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the viewer height here is in feet you

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can just move this up and down if you

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let go or pop back to the middle and

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kind of reset so you have to keep

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dragging it and you can get higher and

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higher as you expect as you get higher

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you can see more and more I'm just going

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to reset that again if you click on

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refraction on and off it's fairly

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straightforward standard refraction just

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makes the temperature profile be a

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straight line just getting colder as you

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get higher which it's gonna let the

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standard atmosphere so it gives you like

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it since we can average refraction if

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you look at my curve calculator this

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amount of refraction is what you're

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seeing when I'm calculating what how

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much you should be visible with standard

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refraction I can to the refraction on

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and off vegan you can see this is the

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effect of standard refraction if you

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don't stand it off you get the curve

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back again and you can edit the curve or

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you can get the more interesting effects

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from refraction

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the series click on a level it will show

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you where your eye level is which is

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like zero degrees basically relative to

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the local vertical and you see in this

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situation the horizon is below eye level

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and if we turn off refraction this is

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like it's you know essentially in no

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atmosphere you can see it's below there

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and with standard refraction turned on

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it's below and in with this you know you

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can see that the rear the reflection

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that we're getting in situations like

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this is actually happening below higher

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level or Engler to reset things again

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because I'm messing up fewer offsets

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just a simple thing you can move things

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left and right it's going to useful to

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you know to set up a nice scene like

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saying I wanted to do this so you can

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see this know what this window actually

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is I should probably explain that this

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window is essentially the side view it's

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greatly compressed left to right this is

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showing you the curve of the earth this

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is where your camera is and this is

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where the target is so this represents

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the full height of the target image and

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you can see where this yellow line is

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here and where the yellow line is there

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like it's touching the top of the CN

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Tower that's the top of those clouds

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which is where the top of the images the

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red and the blue lines that registry

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presenta lines that are going up the

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blue represent lines that are going down

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from your point of view so you can see

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if we turn on high level yeah you can

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see that right here between the red and

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the blue is where your eye level is if

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you turn off refraction you can see it's

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just gonna be perfectly straight there

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with the red going up and the blue lines

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going down and this is more apparent if

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you increase the viewer height to be a

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much higher altitude

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the next thing to look at is the

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vertical Buell vertical fov which is

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perhaps a little of a long-winded way of

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putting things but this is basically the

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field of view vertically for the entire

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screen and here it's set to 1.5 degrees

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this is essentially the zoom on a camera

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but I'm expressing in terms of field of

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view I should perhaps there also put the

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millimeter equivalent zoom there a p900

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Nikon P 900 is about point 6 vertically

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so this would be the maximum zoom of a

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nikon p900 for this particular scene

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yeah let's see if your tilt you can just

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tilt the scene up and down let's just

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just you can get into a good position

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doesn't really change what it actually

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looks like then here there's a field

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called what's the image files this

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allows you to put in your own image

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files you could go to Google Images and

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I could do something like type in Tower

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Bridge find a nice straight on picture

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of Terra bridge here we go and let me

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just see I can do a copy image address

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and stick this in here I'm not sure this

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is going to work on that

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BAM there you go so you'd have to

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actually once you've put in a target

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file then you have to put in the target

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height it's 2,000 here I think Tower

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Bridge is probably more like 800 feet or

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something like that and for less than

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let's say 500 feet not even that or is

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it like 300 feet anyway sir you would

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have to look that up you can see it's

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hidden behind the horizon there now a

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target distance is the distance to the

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hook to that target so I can bring it a

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little bit closer good bit more

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realistic looking this is in miles

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target height as in feet I kind of mix

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the units a little bit sorry about that

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next two things multiple you can

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actually make multiple versions of an

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image so if I put in four and then put

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in say like 3000 feet

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it makes four copies of this particular

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image you can actually see them though

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cuz they're all behind one another I

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think if I change the offset you might

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be able to see how they do

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behind each other has changed this gap

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to 10,000 yeah yep you can see them

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going off into the distance so you can

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set up with multiple multiple images

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this your en lines is just the density

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of lines here it's not very important

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wavelength is the wavelength of light

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that I assume for the calculations if

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you want you could try changing it to

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something else like for example infrared

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lights it's going to be around 1500 and

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nanometers so you can change that you

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can see it makes a very very slight

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difference to what you're actually

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seeing now probably the more interesting

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thing here is all the different presets

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right for example see Catalina from

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Santa Monica this is a have a classic

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view this is the view from six feet on

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the beach Santa Monica and it's based on

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photographs that I took well when I

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visited a few years ago you get this

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very nice hidden part of Catalina now I

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have a flat earth view you can click on

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Flat Earth it will show you what it will

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look like if the earth is flat

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and this is what it should look like

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from six feet if the earth is flatter

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this is actually with refraction down

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refraction of people actually look like

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that you see there's a huge amount of

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Catalina Island down here this is twin

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harbors down here just gonna behind this

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this thing here but what you actually

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see and what you see in my photographs

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is the nun flutter of view of the view

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with myth refraction I should turn a

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standard refraction this is what you'll

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expect if it's just a flat curve this is

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what you actually see from Santa Monica

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beach where it's gonna you know pretty

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much by yourself just proves that's the

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you know the ocean is curved there's a

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very very big difference between that

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and this anyway that aside and I'm

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explaining how to use it not what is

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proof what is proving Chicago view of

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Chicago and let's see there's a more

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interesting one the Bedford level

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experiments here is the classic Bedford

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level this is a six mile stretch of

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canal and hopes is showing it as a open

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ocean but you can think of it as it

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being a canal obviously six miles away

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is this bridge now we have to get the

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field of view all the way down to zero

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point one here so we can zoom in so

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that's a very powerful zoom p900 view

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would be more like like this in the full

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frame so yeah you still be able to see

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it you probably want to use the digital

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zoom to see it all the way so we've got

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two things here we have this target

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which is set halfway along and we've got

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00:11:32,379 --> 00:11:29,749
this guy in a boat and we've got our

273
00:11:36,549 --> 00:11:32,389
viewer height set at 14 feet which is

274
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about the height of this target itself

275
00:11:42,400 --> 00:11:39,889
in the middle and this is type height of

276
00:11:43,539 --> 00:11:42,410
this bridge itself and this is a classic

277
00:11:46,960 --> 00:11:43,549
experiment that's done it's a little

278
00:11:48,340 --> 00:11:46,970
hard to visualize perhaps but if it was

279
00:11:50,410 --> 00:11:48,350
there flat earth and I can actually

280
00:11:53,439 --> 00:11:50,420
share that let's turn off refraction go

281
00:11:55,299 --> 00:11:53,449
to Flat Earth view then this this one

282
00:11:57,579 --> 00:11:55,309
here is actually at the top of the

283
00:11:59,799 --> 00:11:57,589
bridge this one here is quite a bit

284
00:12:02,409 --> 00:11:59,809
below because he's looking straight at

285
00:12:03,160 --> 00:12:02,419
it but if we go to the none Flat Earth

286
00:12:04,809 --> 00:12:03,170
view

287
00:12:07,539 --> 00:12:04,819
then this one is above the top of the

288
00:12:09,840 --> 00:12:07,549
bridge completely different and this

289
00:12:11,799 --> 00:12:09,850
kind of is a very good demonstration I

290
00:12:14,379 --> 00:12:11,809
someone care to repeat this we could be

291
00:12:16,179 --> 00:12:14,389
great it's good demonstration of the

292
00:12:19,479 --> 00:12:16,189
curve of the earth and you can play

293
00:12:21,249 --> 00:12:19,489
around with this an interesting thing to

294
00:12:25,960 --> 00:12:21,259
do is you go to the different version of

295
00:12:28,509 --> 00:12:25,970
this the Bedford level boat this has the

296
00:12:32,289 --> 00:12:28,519
viewer heights at a four feet and this

297
00:12:34,869 --> 00:12:32,299
guy in the boat you can actually see

298
00:12:37,509 --> 00:12:34,879
this the this field here target to it it

299
00:12:39,039 --> 00:12:37,519
shows the different targets here so the

300
00:12:41,439 --> 00:12:39,049
Tuda Stargate the main the boat of the

301
00:12:43,539 --> 00:12:41,449
bridge check the men in the boat one we

302
00:12:45,699 --> 00:12:43,549
can change his distance so we can bring

303
00:12:48,729 --> 00:12:45,709
him closer so this is him just a mile

304
00:12:50,109 --> 00:12:48,739
away and you can see he keeps going

305
00:12:51,549 --> 00:12:50,119
further and further and further away but

306
00:12:53,289 --> 00:12:51,559
he doesn't know he disappear even though

307
00:12:54,849 --> 00:12:53,299
he gets all the way to the bridge over

308
00:12:57,579 --> 00:12:54,859
there you can see him now this was a

309
00:13:00,519 --> 00:12:57,589
classic experiment that was done in the

310
00:13:00,909 --> 00:13:00,529
1800s and it was thought by the guy who

311
00:13:03,429 --> 00:13:00,919
did it

312
00:13:04,960 --> 00:13:03,439
Samuel Robbo from that he demonstrated

313
00:13:07,840 --> 00:13:04,970
that the earth was flat because he could

314
00:13:08,710 --> 00:13:07,850
see this guy all the way down to the

315
00:13:10,960 --> 00:13:08,720
bridge where he should actually

316
00:13:12,609 --> 00:13:10,970
disappeared if I turn refraction off you

317
00:13:15,460 --> 00:13:12,619
can see what you would expect to see

318
00:13:18,369 --> 00:13:15,470
which is the guy disappearing smoothly

319
00:13:20,859 --> 00:13:18,379
over the horizon and be completely

320
00:13:22,569 --> 00:13:20,869
invisible at about five miles but he

321
00:13:25,090 --> 00:13:22,579
didn't see any sewage visible the whole

322
00:13:28,479 --> 00:13:25,100
way because they were at was atmospheric

323
00:13:32,470 --> 00:13:28,489
refraction so he was mistakenly assuming

324
00:13:34,059 --> 00:13:32,480
that the earth was in fact flat because

325
00:13:36,519 --> 00:13:34,069
he wouldn't give you vastly distorted

326
00:13:38,739 --> 00:13:36,529
and he wouldn't be able to see him now

327
00:13:40,869 --> 00:13:38,749
another thing that brings up is low

328
00:13:43,900 --> 00:13:40,879
level humidity we can actually edit the

329
00:13:46,749 --> 00:13:43,910
humidity I say to 50% by defaults but we

330
00:13:49,749 --> 00:13:46,759
can edit it using a curve using the same

331
00:13:52,269 --> 00:13:49,759
same curve editor type thing as we do

332
00:13:53,970 --> 00:13:52,279
for a temperature and it's actually

333
00:13:57,100 --> 00:13:53,980
interesting for something like this the

334
00:13:59,259 --> 00:13:57,110
humidity has a quite large effect on

335
00:14:01,059 --> 00:13:59,269
small things that are very close to the

336
00:14:04,150 --> 00:14:01,069
horizon he doesn't have much of an

337
00:14:05,879 --> 00:14:04,160
effect for large scenes but something

338
00:14:07,470 --> 00:14:05,889
like they say can have quite a dramatic

339
00:14:10,059 --> 00:14:07,480
effect

340
00:14:12,400 --> 00:14:10,069
firstly I'm not sure how realistic this

341
00:14:14,799 --> 00:14:12,410
curve is but I'm letting people edit it

342
00:14:18,090 --> 00:14:14,809
and perhaps they'll figure out what the

343
00:14:22,510 --> 00:14:18,100
actual limits to refraction should be

344
00:14:27,040 --> 00:14:22,520
another classic a modern classic is Lake

345
00:14:28,180 --> 00:14:27,050
Pontchartrain I call these pylons in in

346
00:14:32,470 --> 00:14:28,190
England's we call electrical

347
00:14:37,030 --> 00:14:32,480
transmission towers pylons and this uses

348
00:14:39,670 --> 00:14:37,040
the multiple thing here we've got these

349
00:14:41,260 --> 00:14:39,680
targets electrical towers and boats so

350
00:14:43,420 --> 00:14:41,270
this one here has a multiple of 80

351
00:14:45,640 --> 00:14:43,430
targets with a gap of nine hundred and

352
00:14:48,060 --> 00:14:45,650
seventy nine feet in between each one

353
00:14:51,100 --> 00:14:48,070
and I think that this is just the first

354
00:14:53,020 --> 00:14:51,110
target here first target distances in

355
00:14:54,880 --> 00:14:53,030
miles and the subsequent gaps are in

356
00:14:57,790 --> 00:14:54,890
feet again I apologize for mixing the

357
00:14:59,320 --> 00:14:57,800
units and this is a boat which I just

358
00:15:01,840 --> 00:14:59,330
stuck in just to give you something else

359
00:15:04,360 --> 00:15:01,850
to look at you can change the distance

360
00:15:07,630 --> 00:15:04,370
to that one this is a classic because

361
00:15:09,370 --> 00:15:07,640
you can see the curve quite clearly you

362
00:15:11,830 --> 00:15:09,380
can move around from left or right as if

363
00:15:13,930 --> 00:15:11,840
you're moving along the freeway so you

364
00:15:17,110 --> 00:15:13,940
can take this and interesting things we

365
00:15:21,240 --> 00:15:17,120
can do here is that we can actually mess

366
00:15:24,760 --> 00:15:21,250
around with the temperature gradient and

367
00:15:27,250 --> 00:15:24,770
actually kind of flatten out the curve

368
00:15:29,200 --> 00:15:27,260
by moving it this way

369
00:15:30,910 --> 00:15:29,210
and we can actually raise it up and

370
00:15:32,620 --> 00:15:30,920
there's a there's a photograph that

371
00:15:36,720 --> 00:15:32,630
shares this kind of condition we have

372
00:15:39,790 --> 00:15:36,730
very very cold water relative to the air

373
00:15:42,850 --> 00:15:39,800
it can actually make the curve of

374
00:15:44,440 --> 00:15:42,860
refraction go around the earth that's

375
00:15:46,780 --> 00:15:44,450
you know very similar curve to the

376
00:15:50,410 --> 00:15:46,790
actual earth itself and so it actually

377
00:15:51,730 --> 00:15:50,420
makes it look flat which is kind of kind

378
00:15:53,320 --> 00:15:51,740
of annoying when you want to demonstrate

379
00:15:55,360 --> 00:15:53,330
these things but yeah it really works

380
00:15:56,890 --> 00:15:55,370
with things that are fairly close to the

381
00:15:59,470 --> 00:15:56,900
horizon because you need this kind of

382
00:16:01,600 --> 00:15:59,480
steep temperature gradient which you

383
00:16:03,970 --> 00:16:01,610
only really get when it's closer to

384
00:16:05,680 --> 00:16:03,980
water things like distant mountains it

385
00:16:09,310 --> 00:16:05,690
doesn't really work of they're

386
00:16:13,410 --> 00:16:09,320
interesting things this is a simulation

387
00:16:17,710 --> 00:16:13,420
of a fata morgana which is caused by a

388
00:16:20,560 --> 00:16:17,720
steep inversion at this point 100 feet

389
00:16:22,510 --> 00:16:20,570
up the temperature's going down normally

390
00:16:24,510 --> 00:16:22,520
then it suddenly increases as a warmer

391
00:16:27,160 --> 00:16:24,520
layer just yeah two and a half degrees

392
00:16:29,770 --> 00:16:27,170
but that is enough to create this quite

393
00:16:31,840 --> 00:16:29,780
dramatic effects by moving it around you

394
00:16:34,840 --> 00:16:31,850
can see how quickly it can change with

395
00:16:38,470 --> 00:16:34,850
just a very small amount of variation in

396
00:16:40,270 --> 00:16:38,480
these these values this is something I

397
00:16:42,720 --> 00:16:40,280
actually observed from santa monica and

398
00:16:46,120 --> 00:16:42,730
this country duplicate the same thing

399
00:16:50,040 --> 00:16:46,130
and i think it kind of covers a lot of

400
00:16:52,990 --> 00:16:50,050
things over sir there's one flag that's

401
00:16:55,900 --> 00:16:53,000
distant laser spot 3 feet above the

402
00:16:57,220 --> 00:16:55,910
water level and what's interesting is

403
00:16:59,380 --> 00:16:57,230
you can see the laser but you've no idea

404
00:17:01,450 --> 00:16:59,390
what's really going on what that's

405
00:17:04,210 --> 00:17:01,460
because I have this night flag turned on

406
00:17:06,040 --> 00:17:04,220
if you turn off the night flag you can

407
00:17:07,990 --> 00:17:06,050
see you've got this ridiculous amount of

408
00:17:09,760 --> 00:17:08,000
refraction and you just happen to be

409
00:17:12,370 --> 00:17:09,770
able to see this laser just kind of

410
00:17:14,290 --> 00:17:12,380
poking through it and if i zoom out a

411
00:17:14,950 --> 00:17:14,300
bit you're gonna see more what's going

412
00:17:18,280 --> 00:17:14,960
on here

413
00:17:20,170 --> 00:17:18,290
the lasers down here somewhere and if I

414
00:17:22,330 --> 00:17:20,180
move this around you can see us you just

415
00:17:26,410 --> 00:17:22,340
random with it it happened to bump into

416
00:17:28,900 --> 00:17:26,420
view there is again laser down here but

417
00:17:30,310 --> 00:17:28,910
yeah this just shows how difficult it is

418
00:17:33,280 --> 00:17:30,320
to see what's going on when you do

419
00:17:34,800 --> 00:17:33,290
experiments at night I was just white

420
00:17:37,550 --> 00:17:34,810
he's out the way I did this particular

421
00:17:39,410 --> 00:17:37,560
particular configuration

422
00:17:40,910 --> 00:17:39,420
oh I think I pretty much covered

423
00:17:43,700 --> 00:17:40,920
everything that was obvious is a bunch

424
00:17:46,340 --> 00:17:43,710
of different examples in there that you

425
00:17:48,140 --> 00:17:46,350
can look at this is this is this pose is

426
00:17:51,080 --> 00:17:48,150
actually in my book escaping the rabbit

427
00:17:54,890 --> 00:17:51,090
hole and you can do things like select

428
00:17:57,440 --> 00:17:54,900
the book the boat sailboat here and move

429
00:18:00,530 --> 00:17:57,450
it closer or further away and you'll see

430
00:18:03,140 --> 00:18:00,540
it disappear Hey yes this is a situation

431
00:18:04,280 --> 00:18:03,150
I just had a fairly boring temperature

432
00:18:07,250 --> 00:18:04,290
curve you can actually make it more

433
00:18:10,340 --> 00:18:07,260
dramatic cold the water is what normally

434
00:18:12,980 --> 00:18:10,350
happens and see what happens just mess

435
00:18:14,480 --> 00:18:12,990
around with it see what effect cooling

436
00:18:16,980 --> 00:18:14,490
things down as you can see it there for

437
00:18:19,799 --> 00:18:16,990
longer and you see more compression

438
00:18:21,690 --> 00:18:19,809
and I think yeah I think I pretty much

439
00:18:24,149 --> 00:18:21,700
covered it well like it was how to use

440
00:18:28,039 --> 00:18:24,159
it now you might want to set up your own

441
00:18:31,500 --> 00:18:28,049
things you can add a new target and you

442
00:18:33,570 --> 00:18:31,510
will it just basically duplicates the

443
00:18:35,760 --> 00:18:33,580
pre-existing target I'm gonna expand

444
00:18:38,430 --> 00:18:35,770
this later so you can select which image

445
00:18:39,000 --> 00:18:38,440
to use it doesn't really let you do that

446
00:18:41,310 --> 00:18:39,010
right now

447
00:18:44,850 --> 00:18:41,320
and you can do various multiples of

448
00:18:46,590 --> 00:18:44,860
things if you want to if you get a nice

449
00:18:49,320 --> 00:18:46,600
set up so you know you think I want to

450
00:18:53,909 --> 00:18:49,330
share this with people this particular

451
00:18:56,730 --> 00:18:53,919
scene you can click on permalink and it

452
00:18:58,830 --> 00:18:56,740
will give you a link on the top here

453
00:19:00,389 --> 00:18:58,840
very long a link but you can still just

454
00:19:03,049 --> 00:19:00,399
take it and post it you can post it in a

455
00:19:05,899 --> 00:19:03,059
forum post so it usually works on

456
00:19:08,610 --> 00:19:05,909
youtube or on Facebook or even Twitter

457
00:19:10,620 --> 00:19:08,620
and this will take them directly to this

458
00:19:13,980 --> 00:19:10,630
scene you just reload that now it takes

459
00:19:15,510 --> 00:19:13,990
you to the exact same scene which is

460
00:19:18,840 --> 00:19:15,520
quite handy for sharing it there's

461
00:19:24,299 --> 00:19:18,850
another button here export which will

462
00:19:27,330 --> 00:19:24,309
create a text version of the data which

463
00:19:29,760 --> 00:19:27,340
I can then like stick into my code so if

464
00:19:32,220 --> 00:19:29,770
you have a nice set up then I can take

465
00:19:36,899 --> 00:19:32,230
that and put it into the code as a

466
00:19:40,019 --> 00:19:36,909
preset this link here will take you to

467
00:19:42,539 --> 00:19:40,029
the discussion thread and I think I

468
00:19:46,350 --> 00:19:42,549
think that is pretty much everything so

469
00:19:50,639 --> 00:19:46,360
yeah I if you've got any suggestions I

470
00:19:52,320 --> 00:19:50,649
would be happy to add things to this a

471
00:19:54,269 --> 00:19:52,330
couple things I didn't say you can turn

472
00:19:56,730 --> 00:19:54,279
this side view on and off you can also

473
00:19:59,549 --> 00:19:56,740
make it turn off the gradient so you can

474
00:20:01,380 --> 00:19:59,559
see the lines a bit easier ignore this

475
00:20:03,260 --> 00:20:01,390
debug thing it's meaningless is just a

476
00:20:06,260 --> 00:20:03,270
test thing for me

477
00:20:08,240 --> 00:20:06,270
yeah yeah so if you have any suggestions

478
00:20:12,140 --> 00:20:08,250
just let me know and I will be happy to

479
00:20:13,340 --> 00:20:12,150
add it given time over the next weeks

480
00:20:15,620 --> 00:20:13,350
and months because I'm actually quite

481
00:20:18,440 --> 00:20:15,630
enjoying messing around with it and