Getting geo position from photo texture filenames?

[Guest luissa]

Hi,Yes, it should be N+2. The answer to your question is yes. FS uses a Geographic Projection of the Earth. That means that the whole Earth is represented by a rectangle of 360 degrees of longitude by 180 degrees of latitude. I have not tested your program (yet!) and I do not know if you are using (or not) constant width Areas (or LOD13 squares). I think you should take this into account. For example at a latitude of N40 the Areas are about 1.2km x 1.2 km. But in the equator they are larger (1.2km x 1.6km). And, near the poles, they are very thin. Here is a table:http://www.ptsim.com/downloads/sdk_lod.htmwhere you see that the dimension of the LOD13 quad is 1221 meters (height) by 1628 meters (width) at the Equator. The height is constant. The width decreases with latitude and a simple formula is:width = 1628 * cos( latitude)Hope this information is useful,Luis

[Guest artmartin]

Well if the height of the Lod13 quad is constant then that should imply that for each row of tiles that the latitude values are exactly the same. That makes things easy for ordering the tiles then. Simply have to order the columns within each row by their longitudes and their position on the full mosaic is simple to compute. I'm really not dealing with the low level cartographic calculations at all in my program. The texture files are a fixed size in pixels (256 X 256) and that's the easiest way to deal with them in multiples of that size. Trying to skew them for the tiny differences over the small distances they represent would be an exercise in futility. All FS cares about in regards to entries in an .agn file is their relative location within a 1 X 1 grid (from -.5 to +.5). Nothing is coded to lat/lon. Only reason I'm even caring about texture tile physical locations on the world is to create a mosaic of those tiles to give the user an easier way of deciding which tile to edit in a huge scenery area. I can only show about 60 adjacent tiles on a screen at one time anyway so even if there's quite a skew across the entire scenery image, it'd be pretty unnoticeable over a 10 tile wide grid. Art

[GHD 21]

>I started creating my mosaic display by>using the assumption that all tiles on the same row>would have the same latitude value and all tiles in>a column would have the same longitude values.>It that a correct assumption with the world not being>perfectly flat? It seemed to work for a directory >that had few tiles but a larger one gave me weird>.... so I may have to do some rounding for my>comparisons.Art,You are perfectly correct, the tiles should align on lat/long. You can use fairly crude rounding as the difference in latitudes for each row is 0.010986328125 deg and longitude (column) is 0.0146484375 deg.George

[Guest luissa]

>Only reason I'm even caring about texture tile physical>locations on the world is to create a mosaic of those tiles to>give the user an easier way of deciding which tile to edit in>a huge scenery area. I can only show about 60 adjacent tiles>on a screen at one time anyway so even if there's quite a skew>across the entire scenery image, it'd be pretty unnoticeable>over a 10 tile wide grid. Hi Art,I agree this is not very important for the anotation part of scenery design. Since I introduced this discussion here allow me to develop a litle further (I could start a new thread, but I think it is best to keep things together). In making photo scenery we must georefernce our phototiles. In extreme north (and south) regions that means a lot of predistortion. Land class scenery, for example, uses the same undistorted phototiles from the Equator up to (I think) 80 degrees of latitude (N or S). Here are illustrations of this:http://www.ptsim.com/downloads/sbuilder/land70.jpg that shows 4x3=12 land class tiles placed around N70 W10. I also placed the 12 tiles at N0 W10 but unfortunately I did not keep the same zoom:http://www.ptsim.com/downloads/sbuilder/land00.jpgStill, we clearly see the difference on the real size of the LOD13 rectangles. In Flight Simulator these 2 sceneries look like this:http://www.ptsim.com/downloads/sbuilder/fsland70.jpghttp://www.ptsim.com/downloads/sbuilder/fsland00.jpgKind Regards, Luis

[Guest artmartin]

Thought you'd get a kick out of the outcome of all this. Here's a screenshot from the mosaic file browsing page I've created. Works wonderfully. The red boxes are around tiles that already have autogen created, the green for the ones that don't.Arthttp://forums.avsim.net/user_files/112138.jpg