Terrain Positioning: Use Real World Coordinates, Scale coordinates or just 0,0,0

Unity Engine
1

Hello

I would like some advice on how I should organise my game terrain. My game/application creates the terrain using Google’s Static Maps. So it downloads these satellite images and tiles them together to produce a terrain. It also obtains the real world elevation using Google Elevation.

So I download the satellite image and apply this image to a Plane GameObject as a texture. I am wondering what position I should give these Planes, ie, real world coordinates, ie, a position of -33.33222, 151.45322, 100 or just begin from 0,0,0.

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Would you maintain the world coordinates (Longitude, Latitude, Elevation) inside the game/app or would you just tile these Planes at 0, 0, 0 and go from there? If I use world coordinates it will mean that these Planes will have a tiny scale of 0.006866455 by 0.1 by 0.006866455 (x, y, z). This is because the real world width and height (in degrees) of each satellite image is 0.006866455 degrees. This might cause some tricky collision detection down the track do you think? Ie, working with such small numbers may make collision detection less efficient? But having real world coordinates will help with setting elevation easily, ie, if the real world elevation of -33.74857, 151.2321 is 100.5 then I wont need to convert this Long, Lat to game coordinates.

Would you maybe scale the coordinates up by a factor of 100. So a Plane representing the real world coordinate of -33.74857, 151.2321, 100 would be placed in the game at -3300.74857, 15100.2321, 10000 and the planes scale would be 0.6866455 by 10 by 0.6866455 (x, y, z). Or would you just not bother and just start placing the Planes at 0, 0, 0 with a scale of 1, 1, 1 and go from there?

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2

it all depends on what you have planned down the line. In the documentation it is recommended to use real world sizes for the physics engine to work properly.

Så basically that is what sets the standard and what should dictate the size, if you are going to use physics.

Then where you place your objects in world space really doesnt matter as long as YOU have some sort of system to know where wich tiles is where. i would try to size my tiles to a size that is easy to multiply and is same langth and width. like 1024x1024 for each tile. then maybe store tiles in an object. Stuff all these objects in an array, and each object contains the texture, the long and lats, and their actual position in world space ingame.

but as i said, physics engine is the one dictating the size.

3

Thanks for your reply :slight_smile: I think I might stick to 1,1,1 scale and 0,0,0 positioning and convert game coords to world coords. Seems the easiest.

4

Hey i am pretty new to unity and am really interested in how you did all this. Can you tell me how you learned to do this? or any available tutorial you can point me to that will help me learn this. Would really appreciate the help.

5

doesnt get simpler than this