I need to find all pixels with a certain value and create a shapefile from those locations. Any idea how to get started ?
You may use a simple workflow (a bit annoying, but it could be easily implemented in the QGIS Modeler if you need to perform it for several values).
1) Generate a grid of points
Generate a grid of regular points centered on the pixel centroids of your raster. You may use the Regular points algorithm from Processing:
- The first parameter is the extent of your input raster (you may select it from the ... button on the right);
- The second parameter is the size of your input raster (you may select it from the ... button on the right):
- The third parameter is the half of the size of your input raster (you may select it as above, but remember to divide the size by two).
This will be the result:
2) Add raster values to points
Use the Add raster values to points SAGA tool from Processing (it doesn't need more explanation).
3) Extract the point of interest
Use the Extract by attribute algorithm from Processing and select the value you need (in my example, equals to 1880):