Rob's workflow on the
"GeoTIFF Export Options" dialog >
[Tiling Tab] is good practical advice; the size entered there varies with:
* the overall size of the area on the ground that you intend to cover with your custom photo-real land class terrain textures
* whether your custom photo-real land class terrain textures includes extra Water_Mask and Blend_Mask Alpha channels
* whether your custom photo-real land class terrain textures includes 'extra' seasonal variation and night (aka "LightMap") textures
NOTE: IIRC, in some scenarios, 'extra' texture sets may increase a base 'single texture set' file size
5X to 6X ...regardless of whether "compression" is applied to the BGL; this may compel use of Global Mapper tiling options as Rob describes above.
SDK Resample output BGL file size can be minimized somewhat by use of a "NullValue" parameter / value in the INF file where applicable.
FYI: A good practice indeed is, to limit custom photo-real land class terrain texture BGL output size to
less than 2GB each.
Although some may wish to limit each such files to less than 1.5 GB, 1 GB, or even 500 MB each, it is AFAIK not 'required' to do so, as FS does
not load the 'entire 'file in memory; rather, it loads '
pointers' to sub-sections within that file, and reads only imagery data portions it needs and/or will 'soon' need ...based on Geographic coordinates and heading of the user aircraft at run time in MSFS / P3D.
BTW: If it is necessary or desirable
ex: to more quickly test output for a
smaller area:
In
Global Mapper Menu > File > Export > Export Raster Image Format > ("Select >"GeoTIFF") >
GeoTIFF Export Options dialog:
In"
GeoTIFF Export Options" dialog >
[Export Bounds Tab]
Select "All Loaded Data"
Click
{"
Draw a Box..."} button and select
only an area of interest for that particular GeoTIFF export file output.
[
EDITED]
Regarding
ECW (aka "
Enhanced Compression Wavelet") file format:
these source files may be lossy-compressed JPEG2000 imagery, so one must be careful with algorithms used to re-project and inter-convert this file format.
https://en.wikipedia.org/wiki/ECW_(file_format)
PS: When you process your source aerial imagery file(s):
If a typical graphics application reads and opens these files as a form of JPEG / JPG file, and the image is re-saved after opening, progressive loss of resolution and sharpness, "halo scatter" etc. may occur with each and every "save" operation.
CAVEATS: One should, IMHO, always:
* immediately make
back-ups of such original source files
* immediately make a
copy of those files "converted" to a
non-lossy file format ex: GeoTIFF
* only work with
copies of those files "converted" to a
non-lossy file format for editing etc.
*
never "
re-size" image pixel dimensions (by adding or deleting Rows+Columns of pixels), as this alters / loses image projection relative to the original Geo-referencing information within the Geo-TIFF file.
*
back-up to an external file via special GIS utility, the original Geo-referencing information within the Geo-TIFF file before graphical editing as a "TIF" file.
*
restore the original Geo-referencing information via the "
same" special GIS utility into the (non-re-sized) "TIF" image file after graphical editing (...to convert it back into a Geo-TIFF).
To assist with making back-ups of the original Geo-referencing information within the Geo-TIFF file via special GIS utility
before graphical editing as a "TIF" file, during initial export from Global Mapper, add these 2 options to those already listed in my post above:
http://www.fsdeveloper.com/forum/threads/global-mapper-export-question.434552/#post-715864
In
Global Mapper Menu > File > Export > Export Raster Image Format > ("Select >"GeoTIFF") >
GeoTIFF Export Options dialog:
In"
GeoTIFF Export Options" dialog >
[GeoTIFF Options Tab]
Check
"Generate TFW (World) File
Check
"Generate PRJ File (aka '
projection' info)
[
END_EDIT]
Hope this helps a bit more !
GaryGB