New answers tagged coordinates
With libtiff you can't get altitude from you file. I spent a lot of time trying to do it with libgeotiff. My advice is to install GDAL. Example: GDALRasterIO( hBand_ , GF_Read , p, l, 1, 1, &pafScanline, 1, 1, GDT_Float32, 0, 0 );
You first need to import the CSV and give it which fields are x and y co-ordinates and the projection of your data. This should be the large comma icon which says Add Delimited Text Layer. If you then go to the Vector menu (you may need the Ftools plugin installed but this comes as standard in recent versions of QGIS I believe) then Analysis, you have a ...
You may have swapped the coordinates somewhere. If I reproject your resulting lonlat coordinates 103.919768 1.125312 103.690059679 1.35650722603 I get with cs2cs using: cs2cs -f "%%.6f" +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs +to +proj=tmerc +lat_0=1.366666666666667 +lon_0=103.8333333333333 +k=1 +x_0=28001.642 +y_0=38744.572 +ellps=WGS84 ...
Have you tried right clicking on your XYSites feature class and selecting "Zoom to Layer"? If you can see them, and they are not overlappign your raster coverage, you have a Projection problem.
As nobody provided an answer and meanwhile I created a solution, I will post it as an answer. The main problem was, that I was thinking in a cartesian plane, while the projection is based on a sphere. It worked in some situations, while failed in other cases. The task is to filter out these cases. I changed the averaging formula a little to add more ...
My preferred solution is to build a custom CRS in QGIS, and test if sample coordinate points are placed correctly compared to Openstreetmap or Google imagery from the openlayers plugin. In Russia, Gauss-Krüger transverse mercator based on the Krassnowsky ellipsoid is common use. The projections named Pulkovo are usually 3 or 6 degrees wide, with a false ...
I recommend ProjFinder. The principle is "zoom on the place you are looking for and the tool will provide the supposed projections". You can also use epsg.io and search Russia to sort out possible projections
Based on Identifying Coordinate System of Shapefile when Unknown? it directed me to a tool which is very helpful to find relevant CRS which is exactly I was hoping for: http://www.epsg-registry.org/ The result in my case:
1) Looks good, but you can crop, warp and convert data into XYZ with a single command by addind parameter -of XYZ to your gdalwarp command. However, some file formats are not good targets for gdalwarp which must append data to initialized target while the warping process is progressing. Make a trial and test if using tiff as on interim format is faster or ...
Top 50 recent answers are included