gdal – How to Georeference Himawari-8 in GDAL or Other Tools

gdalgdalwarpgeoreferencingproj

Does anyone know the appropriate project information to georeference (and hence reproject) Himawari-8 AHI data in the IR?
The images are 5500×5500 pixels.

Currently I try these:

ulx=-5570248.832537 
uly=5570248.832537 
lrx=5567248.429179 
lry=-5567248.429179 
gdal_translate -a_srs  "+proj=geos +a=6378169 +b=6356583.8 +lon_0=140.7 +h=35785831" -a_ullr $ulx $uly $lrx $lry HDF5:"TEST"://img tmp.tif

gdalwarp -srcnodata -32767 -s_srs '+proj=geos +lon_0=140.7 +h=35785831 +x_0=0.0' -t_srs '+proj=latlong +datum=WGS84' -tr 0.03 0.03 -te 55.7 -80 225.7 80 -order 3 tmp.tif FINAL.tif

This, however, results in an image that's not quite right.
Australia and Indonesia almost match a coastline boundary overlay but as one moves further from the subsatellite point there exists a larger and larger offset. See this comparison image:

If someone could point me to the correct code to use for reprojection that would be great. I suspect it's the a_ullr values that I have wrong.

Best Answer

Your assumption is right, you need the correct values for the corner coordinates.

Since the source image is slightly larger than the Earth, you can not simply reproject the corner coordinates. You may use a different approach:

According to the project site, the 5500x5500pix data is providing a 2km resolution on the center. So the extent from the center is 5500/2*2000m = +/-5500000m.

With that, and the WGS84 ellipsoid data, I used this transformation:

gdal_translate -a_srs "+proj=geos +h=35785863 +a=6378137.0 +b=6356752.3 +lon_0=140.7 +no_defs" -a_ullr -5500000 5500000 5500000 -5500000 PI_H08_20150125_0230_TRC_FLDK_R10_PGPFD.png temp.tif
gdalwarp -overwrite -t_srs "+proj=latlong +ellps=WGS84 +pm=140.7" -wo SOURCE_EXTRA=100 temp.tif Himawari8.tif

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[GIS] Georeferencing using GDAL

follow this way:

Find your spatial reference code from here
Learn your tif file upper left coordinate and lower right coordinate.
use this command for making it coordinated:
- gdal_translate -of GTiff -a_ullr ullon ullat lrlon lrlat -a_srs EPSG:4269 input.tif output.tif
use this command for mercator:(epsg:3857)
- gdalwarp -of GTiff -t_srs EPSG:3857 input.tif output.tif
then use gdal2tiles.py to tile.

[GIS] Georeferencing png using gdal

Here's a world file for you (as per Gene's suggestion). Cut and paste the following into a text editor and name the file the same as your full-sized map but give it the extension '.pgw' instead on '.png':

1.0
0.0
0.0
-1.0
0.0
3231.0

I've made the following assumptions:

Your map has a resolution (pixel size) of 1m square (i.e. each pixel is a reasonable stride length for a fantasy game humanoid character). If I am wrong, edit lines 1 and 4 accordingly.
I have assumed that your map is not rotated.
I have assumed that your LL corner is at 0,0 in your world. If your pixel size is bigger than 1m square then you will need to multiply your Y coordinate (3231.0) accordingly.
Technically the UL coordinate (last two lines) is the center of your pixel. I have been lazy and set it to the corner. This in theory means that your coordinates would be consistently half a meter out but it's a fantasy world so nobody will know; it is consistent so won't screw up any distant calculations; and it saves a negative value as one of your origin coordinates. Adjust if you are sufficiently worried :)

I would then re-tile your map from the georeferenced full-sized one (this saves you making a world file for each tile)

Now, if you load your fantasy map into a GIS or similar system, you will probably be asked for the Spatial Reference System (SRS). The World file doesn't encapsulate that. It just locates and orients the image file in space relative to a nominal 0,0 origin. Since this is a fantasy map, all you need to do is pretend that it is in the real world somewhere and pick any coordinate system that gives you a flat projection with units in meters (or feet if you prefer but you will may have to adjust the values for resolution in the world file). A couple of suggestions for SRS could be:

EPSG: 3857 (aka 900913)
EPSG: 27700 (UK National Grid - the advantage of a national grid system UK or otherwise, is that you mostly stay clear of the poles and the international dateline and can hopefully avoid any weirdness which may result from such a location)

Your choice might not matter at all... on the other hand, you choice of SRS might be influenced by what you intend to do with your KML/CSV file (like you might be making a game with a post-apocalyptic theme but set in Quebec ...with zombies...). If you are using Google Earth or similar as a 'platform' for your game/fantasy world, so long as all your other data are in the same coordinate system, all should be well.

However, I do wonder if you may be better sticking with your PNG file as a text format like KML/CSV will be big. A PNG may be better for an internet-based game (reducing bandwidth). If you have a stand-alone scenario, most programming languages understand image formats well (especially if you call the GDAL libraries) and so I'm not convinced that a text-based format is even necessary here - but that's your choice of course.

Best Answer

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[GIS] Georeferencing using GDAL

[GIS] Georeferencing png using gdal

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