ArcPy.da.SearchCursor not cursor-ing

Question

I am using ArcMap 10.8.1.

I have shapefiles that are a series of overlapping polygons of drone imagery footprints. I want to loop through each shapefile, and for every shapefile loop through and rasterize every polygon/row in each of those shapefiles. I wrote some code that I adapted from here (Polygon to raster: Creating 1 raster for each polygon in feature class) where I:

• find a list of all the shapefiles that end in "*footprints.shp" in an intermediate STEPS folder
• create an output subfolder in STEPS\rasterfootprints for each file I process to contain the rasterized footprints
• SearchCursor through and create rasters of each polygon in the shapefile.

The following code executes:

import arcpy
import math
import os

root = r"C:\users\myusername\Desktop\ORTHO_FOOTPRINT_AUTOMATION" #change the filepath here
inputs = root + r"\INPUT_CSVS" #input directory of geotag CSVs
steps = root + r"\STEPS" #location of temporary file storage of intermediate processing steps
rfoots = root + r"\STEPS\rasterfootprints" #subfolder in steps to store the 100's of rasterized individual photo footprints
outputs = root + r"\OUTPUT_SHAPEFILES" #location of final

arcpy.env.workspace = steps
arcpy.env.overwriteOutput = True
shplist = arcpy.ListFiles("*footprints.shp")
for shp in shplist:
    prefix = shp.rsplit('footprints.shp')[0]
    os.makedirs(rfoots + '\\' + prefix)
    outfolder= (rfoots + '\\' + prefix)
    PIDname = "PID" #Sequential PhotoID field
    InFeatures=shp
    with arcpy.da.SearchCursor(shp, PIDname) as sCur:
        for row in sCur:
            out_Raster = "PID{}.tif".format(row[0])
            arcpy.MakeFeatureLayer_management(shp, "Layer")  # make a new layer
            arcpy.PolygonToRaster_conversion(shp, "COUNT", os.path.join(outfolder, out_Raster))
            arcpy.Delete_management("Layer")

But it seems to ignore the search cursor through the field "PID" (type:Long) and produces the same raster of the entire area (i.e. a raster of ALL photo footprints) for every file that should be of a single photo.

When it should be giving me something like this (created from running manually in QGIS):

This is what my attribute table looks like:

What do I need to change in my script?

Answer 1

You are creating the same feature layer for each row, and the layer is the entire shapefile. Then rasterizing the shape.

Add a where clause to only make a feature layer of current cursor row and rasterize "Layer" :

...
with arcpy.da.SearchCursor(shp, PIDname) as sCur:
    for row in sCur:
        out_Raster = "PID{}.tif".format(row[0])
        sql = """{0} = {1}""".format(arcpy.AddFieldDelimiters(datasource=shp, field=PIDname), row[0])
        arcpy.MakeFeatureLayer_management(in_features=shp, out_layer="Layer", where_clause=sql)
        arcpy.PolygonToRaster_conversion("Layer", "COUNT", os.path.join(outfolder, out_Raster))
        arcpy.Delete_management("Layer")
...

Answer 2

And if it helps I have this Python code that uses arcpy 2.7 to create a new raster from a feature class of drone image footprints. The raster values are the number of overlapping images at each pixel.