| 104 | | We downloaded 13 zipped files, the ones covering our caribou dataset. Since we don't provide you with the caribou points (you will generate them, randomly yourself), you can download the SRTM files you want. Download about ten of them for a real example. Once downloaded, if you have 7-Zip installed, you can simply select all the zip files, right-click on them and select "7-Zip->Extract files..." 7-Zip will extract every TIF file in the same folder. Each file is 6000 pixels wide by 6000 pixels high. You can quickly preview the images if you have a good images viewer like !IrfanView installed. Efficient raster/vector analysis with PostGIS WKT Raster requires raster files to be split into tiles when loaded in the database. Fortunately gdal2wktraster.py has an option to tile the images the size we like. We will tile them into 50 pixels x 50 pixels resulting in 6000/50 * 6000/50 * 13 = 187200 tiles. gdal2wktraster.py also accepts wildcard so we will be able to load our 13 big rasters in one unique command. |
| | 104 | We downloaded 13 zipped files, the ones covering our caribou dataset. Since we don't provide you with the caribou points (you will generate them, randomly yourself), you can download the SRTM files you want. Download about ten of them for a real example. Once downloaded, if you have 7-Zip installed, you can simply select all the zip files, right-click on them and select "7-Zip->Extract files..." 7-Zip will extract every TIF file in the same folder. Each file is 6000 pixels wide by 6000 pixels high. You can quickly preview the images if you have a good images viewer like !IrfanView installed. |
| | 105 | |
| | 106 | Efficient raster/vector analysis with PostGIS WKT Raster requires raster files to be split into tiles when loaded in the database. Fortunately gdal2wktraster.py has an option to tile the images the size we like. We will tile them into 50 pixels x 50 pixels resulting in 6000/50 * 6000/50 * 13 = 187200 tiles. gdal2wktraster.py also accepts wildcard so we will be able to load our 13 big rasters in one unique command. |
