Professional Advice needed: landclass

[roland 28]

I am having a mess with my landclass files/folders and need help:Under Addon Scenery I have a seperate landclass folder with subfolders for each landclass scenery. Until now my understanding was we have to use mesh with the lowest priority, then landclass and then finally individial scenery add ons with the highest priority.My question now is how to set the priority among different landclass folders if several folders exist for the same area. Here's an example:MyWorld landclass (payware add-on) lowest priorityAfrica landlcass (more detailed freeware add-on for Africa only)South Africa landclass (even more detailed for SA only)South Africa Airport landclass (lc just for airport area) highest priorityDoing a search I have come across a post stating that with landclass it's the other way around: the lower the priority, the more importance.Can that be true???

[scott967 62]

I think you will find that mesh, landclass, and other scenery are treated separately, so the priority between categories doesn't matter. I think it does help, though, to group these categories for ease of management.When landclass or photo scenery covers the same geo area, the highest priority file will be used. For addon landclass, it is possible for the developer to use a landclass value of "254" for transparent, meaning the landclass value for a lower piority file will continue to be used. The lowest priority is the default landclass file, worldlc.bgl. Thus, the "best" landclass should be installed at the highest priority level, relative to any other landclass files covering the same geo area.Or, if some one has a reason for doing it another way, I would like to read it.scott s..

[roland 28]

Scott, many thanks for the explanation. Makes a lot of sense to me.I will now play around with my different LC folders for the same area by activating/deactivting indivial folders and see.BTW if on the ground on the runway or just after take-off for say up to 3000 feet does landclass come into play in one way or the other or is that all just autogen scenery?Roland

[scott967 62]

The landclass file defines a set of textures which will be drawn over the terrain elevation mesh, and the autogen objects which will be placed on the mesh. At close distance, the full resolution textures are blended with the neighboring ones so that the tile effect is not so obvious. The blended texture covers an area known as LOD13, which is simply a geo division of the earth surface covering a square about 1.2km on a side.Once the blended texture has been created, any terrain polygons or lines are drawn into the texture. These might be for park areas, streams, roads, etc. The polygons and lines can be arbitrary shape, but are not blended. They simply replace the blended landclass pixels which they cover. You could use a polygon to precisely define a city area. This works well with an aerial photo of the city to use as the texture.It is possible to bypass the entire landclass/polygon system by using photo textures. In this case there is a unique texture bitmap for each LOD13 tile, and they are not blended.the landclass textures are mipped, so at higher view altitude, the mips will be used. I don't know if the mips are blended at all (suspect not). The mips of course have less detail/resolution than the base textures, and if the view position closes in towards terrain that is displaying mipped texture, it will appear "blurry" until the tile can be redrawn with the higher resolution mip (or full resolution). The sliders control how this occurs.Note that the point of the landclass system is to provide a realistic terrain using a minimum of discrete texture bitmaps which must be loaded and held in graphics texture buffers. The sim uses a few tricks, such as regionalized textures, seasonal textures, and slope gradient textures to improve the effect. One side effect of this is that changing the terrain mesh (if it changes the slope gradients) may result in different textures being drawn, even with the same landclass file in use.scott s..