topic Re: How do I slice a raster into different value ranges and calculate the area of each, doing this for many rasters? in ArcGIS Spatial Analyst Questions

How do I slice a raster into different value ranges and calculate the area of each, doing this for many rasters?

Elijah — Wed, 04 May 2022 08:27:27 GMT

I have many rasters: The task is to slice each of the rasters into different value ranges (e.g, 0 -8, 8.0 -12 & 12.0 -15) and calculate the area of each slice. Somehow, I am not python-wise yet. Being a repetitive process I guess python will come in here. Any help in this regard would be appreciated as I can't imagine doing this manually for all the raster.

Thank you.

Re: How do I slice a raster into different value ranges and calculate the area of each, doing this for many rasters?

JohannesLindner — Wed, 04 May 2022 09:21:49 GMT

You can use the arcpy.sa.Raster class, which has a built-in raster cell iterator:

def get_raster_areas(raster_path, upper_bounds): """Returns the areas of a raster that are below the given values. raster_path: str, path to the raster upper_bounds: [float], the upper bounds of your desired value bins """ # get raster object raster = arcpy.sa.Raster(raster_path) # get cell area dimensions = raster.getRasterInfo().getCellSize() cell_area = dimensions[0] * dimensions[1] # initialize the area list upper_bounds.sort() # it's important that upper_bounds is sorted areas = [0 for x in upper_bounds] # loop over the raster cells for row, col in raster: # loop over the upper_bounds for i, ub in enumerate(upper_bounds): # if raster cell value is below upper bound, # add cell_area to the corresponding element in the areas list # and break, so this cell doesn't also get added to the other (higher) bins # (that's why we needed to make sure upper_bounds is sorted) if raster[row, col] < ub: areas[i] += cell_area break # return the area list return areas rp = r"G:\...\DGM1_2017_HB1.TIF" # 100x100m raster of elevations in a coastal town bins = [0, 8, 12, 15] areas = get_raster_areas(rp, bins) for b in range(len(bins)): print(f"elevation < {bins[b]}m: {areas[b]}m²") #elevation < 0m: 33.0m² # below 0m #elevation < 8m: 997968.0m² # between 0m and 8m #elevation < 12m: 0m² # between 8m and 12m #elevation < 15m: 0m² # between 12m and 15m

Re: How do I slice a raster into different value ranges and calculate the area of each, doing this for many rasters?

Elijah — Wed, 04 May 2022 09:48:40 GMT

Thanks Johaness. I will try to see how to manage the codes. I appreciate.

Re: How do I slice a raster into different value ranges and calculate the area of each, doing this for many rasters?

RyanDeBruyn — Mon, 23 May 2022 15:40:35 GMT

You could also look into the SA Reclassify/Slice and Zonal Geometry tools

You could do this in a model builder environement or if wanting to script, Python samples are available on the respective tool help documents.

Good luck.