Hot answers tagged

5

This can be achieved with the help of GDAL's Virtual Raster Format. With this you can essentially skip the step of creating one giant DEM. The VRT will be handled by GDAL like a giant, merged DEM but is just a small XML file containing the file paths for each tile as well as some metadata. This can then be fed to gdalwarp together with a bounding box or a ...


3

For floating-point DEMs, I use -9999 because it's easy to remember, easy to type and, in terms of terrain elevations (in metres), impossible. If you can meet the latter condition, it doesn't really matter what you choose. A lot of climate-related datasets use some variation on the negative-multiple-nines theme, but it's conceivable that some other scientific ...


2

Why does it appear squashed? In the TIFF viewer, the map is in the correct proportions. When a Google map of the same area is overlaid, it matches on-the-ground features almost exactly. Google Maps uses a spherical Mercator projection of WGS84 lat/longs, called WGS84 Web Mercator. Earth is not a sphere, so the Web Mercator projection stretches as a ...


2

You are looking for GDALRasterBand::RasterIO. For efficiency, if you are indexing multiple points, you will want to read data in blocks then index into the resulting array


2

It's a proprietary format, you need a paid license. ERDAS Imagine / ER Mapper ERDAS Geocompressor or GDAL with write ECW/JP2 SDK


2

So, it appears that your TIF is in REAL32 which isn't supported by ECW. It's interesting that you're getting an error, because the writer documentation states that: Any non-eight-bit source data will be rescaled to eight-bit. However, you can force the data to be 8-bit by using a RasterInterpretationCoercer. I would set your output to RGB24 depending ...


1

If you have access to FME, you can convert to ECW fairly easily. Just connect the GeoTIFF reader to an ECW Writer.


1

Personally, I've started using rasterio's windowed read/write However, you can use x and y offsets when writing your array to the output dataset. dataset.GetRasterBand(1).WriteArray(array, xoff, yoff)


1

The accepted answer is probably superior, but I just chose a quick and dirty method to merge files. First I build a index file using gdaltileindex. I then use gdal tools to returns a list of files that the bounding box intersects with. I then use gdal_merge.py to merge them the intersecting DEMs into one large dem and used the crop parameter of gdalmerge.py ...


1

There is an experimental plugin for QGIS called "GeorefExport" that will allow you to export a Geospatial PDF (as well as other formats) maps from QGIS directly. From what I can tell, though, this plugin does not work from a Composer template, just the primary editor map frame.



Only top voted, non community-wiki answers of a minimum length are eligible