To the extent that I can verify what you have written, it looks correct to me. I went and looked at some of the files that have been shared in projects by the pros, and they do indeed seem to be using masks. I also looked at some of my "smaller" output file saves, and as you said, there were no level nine tiles there.
your description conformes mostly to my own experience, so I can agree with your statements.
Let me repeat things which I have been spread in different threads already.
1. aerofly uses image levels. Starting with level 0 it covers the entire earth as a single image. Then each higher level halfes the axes and divides this image into 4 new images. Level 4 has then 16x16 = 256 images.
2. aerofly FS 2 uses the world grid system. The maximum number of tiles in each direction is 65536, the starting tile is bottom left.
So the tile borders don't fit exactly to even coordinates. I published this image for level 4 once before in another thread.
3. No, level 9 is not a multiple of 1 degree as we can see from the description above.
In longitudinal direction we have 512 steps. So calculated the extent of a level 9 tile you end up with 360 degrees / 512 = 0.703125 degrees.
This means close to the equator the extent of a single level 9 tile is about 78 km!
4. This is the code for the tile calculation:Code
- const double tmcoordinates::WorldGridConstantA = 2.3311223704144;
- tmvector2d tmcoordinates::WorldGridFromLonLat( const tmvector2d& lon_lat )
- double x = lon_lat.x / TM_PI;
- double y = lon_lat.y / TM_PI;
- y = tan( WorldGridConstantA*y ) / WorldGridConstantA;
- x = 0.5 + 0.5*x;
- y = 0.5 + 0.5*y;
- return tmvector2d( 65536.0*x, 65536.0*y );
- tmvector2d tmcoordinates::LonLatFromWorldGrid( const tmvector2d& world_grid )
- double x = world_grid.x / 65536.0;
- double y = world_grid.y / 65536.0;
- x = 2.0*(x-0.5);
- y = 2.0*(y-0.5);
- y = atan(WorldGridConstantA*y)/WorldGridConstantA;
- x *= TM_PI;
- y *= TM_PI;
- return tmvector2d( x, y );
5. Please note: The GeoConvertHelper has this formula above built in. Even if you don’t use this tool, you can calculate the borders for your manual editing TMC file. Just click the advanced settings in GeoConvertHelper and activate the level 9 snap.
6. It doesn’t make sense, to create a mosaic of tiny adjacent areas. If you want to create adjacent areas, use a large area and snap to level 9 tile borders. Run the conversion then for level 9-11.
If you do adjacent areas, use a large overlap of your image compared to the TMC frame.
Then you can remove the _mask files.
7. Geoconvert allows you to check your conversion results.
I have mentioned this before, but obviously it is nearly unknown. See or add these lines in your TMC:
With the lines write_raw_files you’ll get png output files which you can check for the content. And you will better understand the tile and mask system.
Don't forget the second line with the images_raw output folder. This folder must exist before you run the conversion.
There exist several approaches to this topic and this is my personal approach, nothing ‘official’ by IPACS. But perhaps it gives you a better understanding of the geoconvert process.
Thank you Rodeo. This is very useful.
Thank you so much Rodeo, you are awesome! That is incredibly helpful. I really appreciate you taking the time to write that all out, and I do apologize if you've already posted that info in other threads and I didn't find it there first. That answers all of my questions and more!
You are welcome.
Jeff does an incredible good job in this forum and I try to assist and take some load off in one of my 'special' fields like sceneries and aerial images.
Since this thread is where all this talk began, I wanted to include a link to a tool that I made for Excel that lets you calculate tile coordinates at any geoconvert level really easily. Info and link is here: Image tile coordinates