For all these years I've avoided scenery files with descriptions like "landclass" or "mesh." I just don't know what they are; How they alter default files; How to do it right and avoid a dreaded CTD.Can anyone tell me? Or point me toward a tutorial that can teach me?THANKS!!Rick (MKE) Now underway, the world's largest outdoor music festival at Summerfest 2006. "Turn Up Your Summer"

A landclass determines what kind of textures FS should cover the ground withusing the default ground textures of the sim or any replacements of them like BirdsEye View, FScene or Ground Environment, and in doing so giving you, depending on the accuracy of the Landclass, a rendition of the real world with it's towns, villages, forrests, fields, swamps, deserts... etc.Mesh is the grid that determines elevation height. The higher the mesh resolution the more the hills and mountains will resemble their real leal life counterparts.That's it for starters. Others can explain why landclass files can cause CTD's.

Normally in the file descriptions, "landclass" refers to a scenery bgl file that alters the default texture definition file, worldlc.bgl. If you imagine the earth as forced into a flat map, with lines drawn N/S and E/W 1.3 km apart, forming a grid, each 1.3km x 1.3 km square of this grid is assigned an integer 0-255 (not all are used). FS9 interprets this integer using various processes to determine the file name of a 256x256 bit texture bitmap from the set of textures in "sceneryworldtexture".This texture is then blended with the textures from the 4 adjoining grid squares to create a final 256x256 bit blended texture which is applied to the computed earth surface geometry (mesh) within that grid square. The addon landclass files typically cover a region of these grid squares such as 256 x 256. By assigning a different integer to a grid square, you can cause a different texture bitmap to be used. A typical reason for doing this, would be that a town exists IRL that is depicted using a crop land texture in the default. To get a town texture to be used instead, the appropriate landclass integers can be entered into the landclass file.The landclass files are installed like other scenery. that is, a parent folder for the scenery area is created, and then a subfolder named "scenery". The landclass file is placed in this subfolder. The scenery library in FS9 is used to add this new folder, make it active, and set its priority. Landclass files follow the normal priority scheme, in that a higher priority scenery area landclass file will replace any lower priority landclass files (including the default) within the area of coverage. There is an FS9 bug. Normally the develper expects to use the normal terrain textures in "sceneryworldtexture". But, when the scenery area folder is added to the scenery library in the typical case one creates not just the "scenery" subfolder, but also a "texture" subfolder. FS9 should look in this local "texture" subfolder first, and then in the "sceneryworldtexture" folder if it can't find it. It does this, but it seems to have a problem managing texture memory and eventually will CTD. For this reason, most developers will recommend that the landclass files be placed in their own scenery areas, not the same one as 3d objects which typically require their own textures in the "texture" subfolder. As long as there is no "texture" subfolder, even an empty one, the landclass file will run properly.scott s..