Geomorphometry II: Spatial and Temporal Terrain Analysis
Resources: ESRI virtual campus
Create the assignment working directory (folder) .\Analysis.
Disable background processing.
Start->Programs->ArcGIS->ArcMap Geoprocessing -> Geoporocessing Options... -> Uncheck "Enable" Background Processing
Compute basic topographic parameters from 10m NED
In ArcMap Select File->Add Data->Add Data... Select ncrast.mdb/elev Check out a Spatial Analyst Extension license Open the ArcToolbox Select 'Spatial Analyst Tools->Surface->Slope' Set 'Input raster' to 'elev' Set 'Output raster' to '.\Analysis\Slope_elev' Set 'Output measurement' to 'DEGREE' Click 'OK'
Do the same for Aspect and Curvature
Try to create a meaningful diverging color table for curvatures with two color shades and light color in the middle.
Compute topographic parameters from SRTM DEM and compare with NED
In ArcMap Select File->Add Data->Add Data... Select ncrast.mdb/elev_srt Open the ArcToolbox (if it's not already open) Select 'Spatial Analyst Tools->Surface->Slope' Set 'Input raster' to 'elev_srt' Set 'Output raster' to '.\Analysis\Slope_el_srt' Set 'Output measurement' to 'DEGREE' Click 'OK' right mouse click 'Slope_el_srt->Properties->Symbology->Classify
Compare mean and stddev in Classification statistics with 10m NED derived slope.
Explain the differences between slope from 10m NED and 30m SRTM.
Compare slope and aspect, from TIN and from 1m raster DEMUse a previously created TIN or create a new one,
see the first assignment of two covering the topic of Spatial interpolation.
In ArcMap Select File->Add Data->Add Data... Select ncshape.mdb/elev_lid792_randpts
Create TIN 'tin' in 3D Analyst from these points if you don't have it already:
Open ArcToolbox (if it's not already open) Select 3D Analyst Tools->Data Management->TIN->Create TIN Set 'Output TIN' to .\Analysis\lid792_tin Set 'Input feature class' to elev_lid792_randpts In the Input feature class list, find the "height_field" (2nd field from left). Click on the entry for the elev_lid792_randpts (Shape_Z is displayed by default). By clicking on the field it should convert to a drop-down list. Click the down arrow to display your list of options and select "Value_". Click 'OK'
The output from this process is a polygon feature class whose attribute (found in the slope class field) consists of the slopes binned into 7 classes.
The default (ESRI) breaks (bins) are at 0.57, 1.43, 2.66, 5.71, 12.13, 24.89, 45.0, 90.0.
Open the ArcToolbox (if it's not already open) Select '3D Analyst Tools-> Triangulated Surface -> Surface Slope' Set 'Input Surface' to 'lid792_tin' Set 'Output Feature Class' as '.\Analysis\lid792_tin_SurfaceSlope' Set 'Slope Units' to 'DEGREE' Click 'OK'
Do the same for Surface Aspect to create: '.\Analysis\lid792_tin_SurfaceAspect'.
As with slope, the aspect that comes from this process is in the form of a polygon feature class whose aspect attribute is binned into eight 45 degree wide
directions (code = 1 - 8 ).
These are: N, NE, E, SE, S, SW, W, and NW, respectively.
Assign suitable colors to the slope and aspect polygons.
Derive slope from 1m raster DEM:
Select File->Add Data->Add Data... Select ncrast.mdb/elid_792 Open the ArcToolbox (if it's not already open) Select '3D Analyst Tools -> Raster Surface -> Slope' Set 'Input raster' to 'elid_792' Set 'Output raster' to '.\Analysis\slope_elid72' Click 'OK'
Choose similar color table as for the TIN. To get more continuous color table:
right mouse click 'Slope_elid72' Select 'Properties -> Symbology" Change Classes to 32 Click 'OK'
Compute the aspect and curvature.
For curvature change the color table to one that has lighter break in the middle.
Compare the resulting slope, aspect and curvature with the topographic parameters derived from TIN.