Enviro

Using Your Own Imagery (Textures)

• Your image needs to match your elevation in both projection and extents.  One way to do this is to use VTBuilder to re-project and crop your elevation, as needed, to match your image.
• If your image is up to 4096*4096 in size (or 8192x8192 for recent 3D hardware), you can use a standard terrain texture.  If it is much larger, you should use an image tileset.

Standard Terrain Textures

• Your imagery should be in either the TIF, PNG, BMP or JPG format.
• Learn how large a texture your computer can display.  From the Enviro Start dialog, press "OpenGL Info..." and look at the number for "Maximum Texture Dimension"
• If your terrain texture map is not larger than the maximum texture, you can use the "Single texture" option, otherwise you will need to use "4x4 Tiled texture".
• Give your texture a filename ending in it's size, e.g. "newyork_1024.bmp"
• Put your texture in in the directory Data/GeoSpecific
• For a Single texture:
  • Your texture size must be a square power of 2, up to the limit of your computer (e.g. 512, 1024)
• For a 4x4 Tiled texture:
  • You provide a single large square image file, and Enviro will break it up for you, at runtime, into a set of 16 tiles (4x4)
  • The size of each tile must be a power of 2, up to the limit of your computer (e.g. 512, 1024)
  • Due to pixel overlap to avoid texture seams, the dimensions of the single large texture may seem somewhat unusual - e.g. 2045 for a 4x4 at 512, 4093 for a 4x4 at 1024
  • The filename is made up of two parts: the prefix (e.g. "hawaii_") and the image size (e.g. "4093"). The dialog lets you specify the prefix, and it computes and appends the image size, based on the tile size you specify
  • So, when you're preparing your image files, simply name them ending in a number that is their size in pixels (e.g. "hawaii_4093.bmp")
  • Click the "JPEG" box for a jpeg texture, otherwise BMP is assumed.

Transparency

• If you provide an image which has an alpha plane (transparency), Enviro will use it.
• Provide a PNG or TIF that is 32-bit, that is, 24 bits of RGB and 8 bits of Alpha.
• You may see some odd effects if you have other transparent objects in the scene, above or below the terrain surface.  This is because OSG/OpenGL cannot always sort transparent objects relative to each other perfectly.

In addition the base texture for a terrain, if you have a modern graphics card with multi-texture, you can use Image Layers to overlay additional textures on your terrain.