def derive_from_dem(dem):
"""derive slope and flow direction from a DEM.
Results are returned in a dictionary that contains references to
ArcPy Raster objects stored in the "in_memory" (temporary) workspace
"""
# set the snap raster for subsequent operations
env.snapRaster = dem
# calculate flow direction for the whole DEM
flowdir = FlowDirection(in_surface_raster=dem, force_flow="NORMAL")
flow_direction_raster = so("flowdir", "random", "in_memory")
flowdir.save(flow_direction_raster)
# calculate slope for the whole DEM
slope = Slope(in_raster=dem,
output_measurement="PERCENT_RISE",
method="PLANAR")
slope_raster = so("slope", "random", "in_memory")
slope.save(slope_raster)
return {
"flow_direction_raster": Raster(flow_direction_raster),
"slope_raster": Raster(slope_raster),
}
def calculate_topographic_properties(**kwargs):
"""
Description: calculates topographic properties from an elevation raster
Inputs: 'z_unit' -- a string value of either 'Meter' or 'Foot' representing the vertical unit of the elevation raster
'input_array' -- an array containing the grid raster (must be first) and the elevation raster
'output_array' -- an array containing the output rasters for aspect, compound topographic index, heat load index, integrated moisture index, roughness, site exposure, slope, surface area ratio, and surface relief ratio (in that order)
Returned Value: Returns a raster dataset on disk for each topographic property
Preconditions: requires an input DEM that can be created through other scripts in this repository
"""
# Import packages
import arcpy
from arcpy.sa import Con
from arcpy.sa import IsNull
from arcpy.sa import ExtractByMask
from arcpy.sa import Raster
from arcpy.sa import Int
from arcpy.sa import FlowDirection
from arcpy.sa import FlowAccumulation
from arcpy.sa import Slope
from arcpy.sa import Aspect
from package_Geomorphometry import compound_topographic
from package_Geomorphometry import getZFactor
from package_Geomorphometry import linear_aspect
from package_Geomorphometry import mean_slope
from package_Geomorphometry import roughness
from package_Geomorphometry import site_exposure
from package_Geomorphometry import surface_area
from package_Geomorphometry import surface_relief
from package_Geomorphometry import topographic_position
from package_Geomorphometry import topographic_radiation
import datetime
import os
import time
# Parse key word argument inputs
z_unit = kwargs['z_unit']
grid_raster = kwargs['input_array'][0]
elevation_input = kwargs['input_array'][1]
elevation_output = kwargs['output_array'][0]
aspect_output = kwargs['output_array'][1]
cti_output = kwargs['output_array'][2]
roughness_output = kwargs['output_array'][3]
exposure_output = kwargs['output_array'][4]
slope_output = kwargs['output_array'][5]
area_output = kwargs['output_array'][6]
relief_output = kwargs['output_array'][7]
position_output = kwargs['output_array'][8]
radiation_output = kwargs['output_array'][9]
# Set overwrite option
arcpy.env.overwriteOutput = True
# Use two thirds of cores on processes that can be split.
arcpy.env.parallelProcessingFactor = "75%"
# Set snap raster and extent
arcpy.env.snapRaster = grid_raster
arcpy.env.extent = Raster(grid_raster).extent
# Define folder structure
grid_title = os.path.splitext(os.path.split(grid_raster)[1])[0]
raster_folder = os.path.split(elevation_output)[0]
intermediate_folder = os.path.join(raster_folder, 'intermediate')
# Create raster folder if it does not already exist
if os.path.exists(raster_folder) == 0:
os.mkdir(raster_folder)
# Create intermediate folder if it does not already exist
if os.path.exists(intermediate_folder) == 0:
os.mkdir(intermediate_folder)
# Define intermediate datasets
flow_direction_raster = os.path.join(intermediate_folder,
'flow_direction.tif')
flow_accumulation_raster = os.path.join(intermediate_folder,
'flow_accumulation.tif')
raw_slope_raster = os.path.join(intermediate_folder, 'raw_slope.tif')
raw_aspect_raster = os.path.join(intermediate_folder, 'raw_aspect.tif')
# Get the z factor appropriate to the xy and z units
zFactor = getZFactor(elevation_input, z_unit)
#### CALCULATE INTERMEDIATE DATASETS
# Calculate flow direction if it does not already exist
if os.path.exists(flow_direction_raster) == 0:
# Calculate flow direction
print(f'\tCalculating flow direction for {grid_title}...')
iteration_start = time.time()
flow_direction = FlowDirection(elevation_input, 'NORMAL', '', 'D8')
flow_direction.save(flow_direction_raster)
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tFlow direction already exists for {grid_title}.')
print('\t----------')
# Calculate flow accumulation if it does not already exist
if os.path.exists(flow_accumulation_raster) == 0:
# Calculate flow accumulation
print(f'\tCalculating flow accumulation for {grid_title}...')
iteration_start = time.time()
flow_accumulation = FlowAccumulation(flow_direction_raster, '',
'FLOAT', 'D8')
flow_accumulation.save(flow_accumulation_raster)
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tFlow accumulation already exists for {grid_title}.')
print('\t----------')
# Calculate raw slope in degrees if it does not already exist
if os.path.exists(raw_slope_raster) == 0:
# Calculate slope
print(f'\tCalculating raw slope for {grid_title}...')
iteration_start = time.time()
raw_slope = Slope(elevation_input, "DEGREE", zFactor)
raw_slope.save(raw_slope_raster)
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tRaw slope already exists for {grid_title}.')
print('\t----------')
# Calculate raw aspect if it does not already exist
if os.path.exists(raw_aspect_raster) == 0:
# Calculate aspect
print(f'\tCalculating raw aspect for {grid_title}...')
iteration_start = time.time()
raw_aspect = Aspect(elevation_input, 'PLANAR', z_unit)
raw_aspect.save(raw_aspect_raster)
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tRaw aspect already exists for {grid_title}.')
print('\t----------')
#### CALCULATE INTEGER ELEVATION
# Calculate integer elevation if it does not already exist
if arcpy.Exists(elevation_output) == 0:
print(f'\tCalculating integer elevation for {grid_title}...')
iteration_start = time.time()
# Round to integer
print(f'\t\tConverting values to integers...')
integer_elevation = Int(Raster(elevation_input) + 0.5)
# Copy extracted raster to output
print(f'\t\tCreating output raster...')
arcpy.management.CopyRaster(integer_elevation, elevation_output, '',
'', '-32768', 'NONE', 'NONE',
'16_BIT_SIGNED', 'NONE', 'NONE', 'TIFF',
'NONE')
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tInteger elevation already exists for {grid_title}.')
print('\t----------')
#### CALCULATE LINEAR ASPECT
# Calculate linear aspect if it does not already exist
if arcpy.Exists(aspect_output) == 0:
print(f'\tCalculating linear aspect for {grid_title}...')
iteration_start = time.time()
# Create an initial linear aspect calculation using the linear aspect function
aspect_intermediate = os.path.splitext(
aspect_output)[0] + '_intermediate.tif'
linear_aspect(raw_aspect_raster, aspect_intermediate)
# Round to integer
print(f'\t\tConverting values to integers...')
integer_aspect = Int(Raster(aspect_intermediate) + 0.5)
# Fill missing data (no aspect) with values of -1
print(f'\t\tFilling values of no aspect...')
conditional_aspect = Con(IsNull(integer_aspect), -1, integer_aspect)
# Extract filled raster to grid mask
print(f'\t\tExtracting filled raster to grid...')
extract_aspect = ExtractByMask(conditional_aspect, grid_raster)
# Copy extracted raster to output
print(f'\t\tCreating output raster...')
arcpy.management.CopyRaster(extract_aspect, aspect_output, '', '',
'-32768', 'NONE', 'NONE', '16_BIT_SIGNED',
'NONE', 'NONE', 'TIFF', 'NONE')
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Delete intermediate dataset if possible
try:
arcpy.management.Delete(aspect_intermediate)
except:
print('\t\tCould not delete intermediate dataset...')
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tLinear aspect already exists for {grid_title}.')
print('\t----------')
#### CALCULATE COMPOUND TOPOGRAPHIC INDEX
# Calculate compound topographic index if it does not already exist
if arcpy.Exists(cti_output) == 0:
print(f'\tCalculating compound topographic index for {grid_title}...')
iteration_start = time.time()
# Create an intermediate compound topographic index calculation
cti_intermediate = os.path.splitext(
cti_output)[0] + '_intermediate.tif'
compound_topographic(elevation_input, flow_accumulation_raster,
raw_slope_raster, cti_intermediate)
# Convert to integer values
print(f'\t\tConverting values to integers...')
integer_compound = Int((Raster(cti_intermediate) * 100) + 0.5)
# Copy integer raster to output
print(f'\t\tCreating output raster...')
arcpy.management.CopyRaster(integer_compound, cti_output, '', '',
'-32768', 'NONE', 'NONE', '16_BIT_SIGNED',
'NONE', 'NONE', 'TIFF', 'NONE')
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Delete intermediate dataset if possible
try:
arcpy.management.Delete(cti_intermediate)
except:
print('\t\tCould not delete intermediate dataset...')
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tCompound topographic index already exists for {grid_title}.')
print('\t----------')
#### CALCULATE ROUGHNESS
# Calculate roughness if it does not already exist
if arcpy.Exists(roughness_output) == 0:
print(f'\tCalculating roughness for {grid_title}...')
iteration_start = time.time()
# Create an intermediate compound topographic index calculation
roughness_intermediate = os.path.splitext(
roughness_output)[0] + '_intermediate.tif'
roughness(elevation_input, roughness_intermediate)
# Convert to integer values
print(f'\t\tConverting values to integers...')
integer_roughness = Int(Raster(roughness_intermediate) + 0.5)
# Fill missing data (no aspect) with values of 0
print(f'\t\tFilling values of roughness...')
conditional_roughness = Con(IsNull(integer_roughness), 0,
integer_roughness)
# Extract filled raster to grid mask
print(f'\t\tExtracting filled raster to grid...')
extract_roughness = ExtractByMask(conditional_roughness, grid_raster)
# Copy extracted raster to output
print(f'\t\tCreating output raster...')
arcpy.management.CopyRaster(extract_roughness, roughness_output, '',
'', '-32768', 'NONE', 'NONE',
'16_BIT_SIGNED', 'NONE', 'NONE', 'TIFF',
'NONE')
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Delete intermediate dataset if possible
try:
arcpy.management.Delete(roughness_intermediate)
except:
print('\t\tCould not delete intermediate dataset...')
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tRoughness already exists for {grid_title}.')
print('\t----------')
#### CALCULATE SITE EXPOSURE
# Calculate site exposure if it does not already exist
if arcpy.Exists(exposure_output) == 0:
print(f'\tCalculating site exposure for {grid_title}...')
iteration_start = time.time()
# Create an intermediate compound topographic index calculation
exposure_intermediate = os.path.splitext(
exposure_output)[0] + '_intermediate.tif'
site_exposure(raw_aspect_raster, raw_slope_raster,
exposure_intermediate)
# Convert to integer values
print(f'\t\tConverting values to integers...')
integer_exposure = Int((Raster(exposure_intermediate) * 100) + 0.5)
# Copy extracted raster to output
print(f'\t\tCreating output raster...')
arcpy.management.CopyRaster(integer_exposure, exposure_output, '', '',
'-32768', 'NONE', 'NONE', '16_BIT_SIGNED',
'NONE', 'NONE', 'TIFF', 'NONE')
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Delete intermediate dataset if possible
try:
arcpy.management.Delete(exposure_intermediate)
except:
print('\t\tCould not delete intermediate dataset...')
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tSite exposure already exists for {grid_title}.')
print('\t----------')
#### CALCULATE MEAN SLOPE
# Calculate mean slope if it does not already exist
if arcpy.Exists(slope_output) == 0:
print(f'\tCalculating mean slope for {grid_title}...')
iteration_start = time.time()
# Create an intermediate mean slope calculation
slope_intermediate = os.path.splitext(
slope_output)[0] + '_intermediate.tif'
mean_slope(raw_slope_raster, slope_intermediate)
# Convert to integer values
print(f'\t\tConverting values to integers...')
integer_slope = Int(Raster(slope_intermediate) + 0.5)
# Copy extracted raster to output
print(f'\t\tCreating output raster...')
arcpy.management.CopyRaster(integer_slope, slope_output, '', '',
'-128', 'NONE', 'NONE', '8_BIT_SIGNED',
'NONE', 'NONE', 'TIFF', 'NONE')
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Delete intermediate dataset if possible
try:
arcpy.management.Delete(slope_intermediate)
except:
print('\t\tCould not delete intermediate dataset...')
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tMean slope already exists for {grid_title}.')
print('\t----------')
#### CALCULATE SURFACE AREA RATIO
# Calculate surface area ratio if it does not already exist
if os.path.exists(area_output) == 0:
print(f'\tCalculating surface area ratio for {grid_title}...')
iteration_start = time.time()
# Create an intermediate surface area ratio calculation
area_intermediate = os.path.splitext(
area_output)[0] + '_intermediate.tif'
surface_area(raw_slope_raster, area_intermediate)
# Convert to integer values
print(f'\t\tConverting values to integers...')
integer_area = Int((Raster(area_intermediate) * 10) + 0.5)
# Copy extracted raster to output
print(f'\t\tCreating output raster...')
arcpy.management.CopyRaster(integer_area, area_output, '', '',
'-32768', 'NONE', 'NONE', '16_BIT_SIGNED',
'NONE', 'NONE', 'TIFF', 'NONE')
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Delete intermediate dataset if possible
try:
arcpy.management.Delete(area_intermediate)
except:
print('\t\tCould not delete intermediate dataset...')
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tSurface area ratio already exists for {grid_title}.')
print('\t----------')
#### CALCULATE SURFACE RELIEF RATIO
# Calculate surface relief ratio if it does not already exist
if arcpy.Exists(relief_output) == 0:
print(f'\tCalculating surface relief ratio for {grid_title}...')
iteration_start = time.time()
# Create an intermediate surface relief ratio calculation
relief_intermediate = os.path.splitext(
relief_output)[0] + '_intermediate.tif'
surface_relief(elevation_input, relief_intermediate)
# Convert to integer values
print(f'\t\tConverting values to integers...')
integer_relief = Int((Raster(relief_intermediate) * 1000) + 0.5)
# Copy extracted raster to output
print(f'\t\tCreating output raster...')
arcpy.management.CopyRaster(integer_relief, relief_output, '', '',
'-32768', 'NONE', 'NONE', '16_BIT_SIGNED',
'NONE', 'NONE', 'TIFF', 'NONE')
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Delete intermediate dataset if possible
try:
arcpy.management.Delete(relief_intermediate)
except:
print('\t\tCould not delete intermediate dataset...')
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tSurface relief ratio already exists for {grid_title}.')
print('\t----------')
#### CALCULATE TOPOGRAPHIC POSITION
# Calculate topographic position if it does not already exist
if arcpy.Exists(position_output) == 0:
print(f'\tCalculating topographic position for {grid_title}...')
iteration_start = time.time()
# Create an intermediate topographic position calculation
position_intermediate = os.path.splitext(
position_output)[0] + '_intermediate.tif'
topographic_position(elevation_input, position_intermediate)
# Convert to integer values
print(f'\t\tConverting values to integers...')
integer_position = Int((Raster(position_intermediate) * 100) + 0.5)
# Copy extracted raster to output
print(f'\t\tCreating output raster...')
arcpy.management.CopyRaster(integer_position, position_output, '', '',
'-32768', 'NONE', 'NONE', '16_BIT_SIGNED',
'NONE', 'NONE', 'TIFF', 'NONE')
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Delete intermediate dataset if possible
try:
arcpy.management.Delete(position_intermediate)
except:
print('\t\tCould not delete intermediate dataset...')
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tTopographic position already exists for {grid_title}.')
print('\t----------')
#### CALCULATE TOPOGRAPHIC RADIATION
# Calculate topographic radiation if it does not already exist
if arcpy.Exists(radiation_output) == 0:
print(f'\tCalculating topographic radiation for {grid_title}...')
iteration_start = time.time()
# Create an intermediate topographic position calculation
radiation_intermediate = os.path.splitext(
radiation_output)[0] + '_intermediate.tif'
radiation_integer = os.path.splitext(
radiation_output)[0] + '_integer.tif'
topographic_radiation(elevation_input, radiation_intermediate)
# Convert to integer values
print(f'\t\tConverting values to integers...')
integer_radiation = Int((Raster(radiation_intermediate) * 1000) + 0.5)
arcpy.management.CopyRaster(integer_radiation, radiation_integer, '',
'', '-32768', 'NONE', 'NONE',
'16_BIT_SIGNED', 'NONE', 'NONE', 'TIFF',
'NONE')
# Extract filled raster to grid mask
print(f'\t\tExtracting integer raster to grid...')
extract_radiation = ExtractByMask(radiation_integer, grid_raster)
# Copy extracted raster to output
print(f'\t\tCreating output raster...')
arcpy.management.CopyRaster(extract_radiation, radiation_output, '',
'', '-32768', 'NONE', 'NONE',
'16_BIT_SIGNED', 'NONE', 'NONE', 'TIFF',
'NONE')
# End timing
iteration_end = time.time()
iteration_elapsed = int(iteration_end - iteration_start)
iteration_success_time = datetime.datetime.now()
# Delete intermediate dataset if possible
try:
arcpy.management.Delete(radiation_intermediate)
arcpy.management.Delete(radiation_integer)
except:
print('\t\tCould not delete intermediate dataset...')
# Report success
print(
f'\tCompleted at {iteration_success_time.strftime("%Y-%m-%d %H:%M")} (Elapsed time: {datetime.timedelta(seconds=iteration_elapsed)})'
)
print('\t----------')
else:
print(f'\tTopographic radiation already exists for {grid_title}.')
print('\t----------')
outprocess = f'Finished topographic properties for {grid_title}.'
return outprocess