Select points situated on zero degree slope

Question

I need to choose points from a shapefile, which are positioned on raster cells with 0 degree slope. Creating a slope raster from DME is not a problem, but I don't know how to write a script that chooses points positioned only on zero slope.

I don't know if use GDAL or it's possible over ArcPy or anything.

Answer 1

This can be accomplished in two steps using the following workflow, assuming you have the ArcGIS Spatial Analyst license:

1. Extract Multi Values to Points (Spatial Analyst)
2. Select (Analysis)

Step 1 adds the raster value (i.e. slope) at each point to the attributes. Step 2 selects and creates a new feature class of all points that meet your condition (i.e. where slope == 0). Note keep in mind this will alter your original point feature class, so make sure to use a copy.

In Python, this would look something like:

import arcpy
from arcpy.sa import *
arcpy.CheckOutExtension("Spatial")

points = r'C:\path\to\your\point.shp' # This should be a copy
raster = r'C:\path\to\your\slope_raster.tif'
outshp = r'C:\path\to\your\output_shp.shp'

# Execute ExtractValuesToPoints
ExtractMultiValuesToPoints(points, raster, "BILINEAR")

#Select points that meet your condition
where_clause = '"slope" = 0'
arcpy.Select_analysis(points, outshp, where_clause)