General

General holds the terrain tools that are not derivatives, classifications or visibility analyses: the ones that make a DEM look right, clean it up when it is damaged, or extract a specific feature from it.

This is where you find shaded relief, which is the most used tool of the whole toolbox, and the repair tools you reach for when a downloaded model has holes, vegetation noise or buildings in it.

Start here

Hillshade

Turns elevation into the shaded relief image that makes terrain readable. Put it under your other layers, at partial opacity, and any map gains depth.

Parameter	What to set
Input	Your elevation raster.
Azimuth	Where the light comes from, in degrees clockwise from north. The default of 315, the north west, is the cartographic convention. Light from the south east makes valleys look like ridges to most readers, an illusion worth avoiding.
Altitude	How high the light sits above the horizon, in degrees. 30 is a good default. Lower exaggerates the relief, higher flattens it.
Z factor	Vertical exaggeration. Leave at 1 when vertical and horizontal units match.
Output	The shaded relief raster, in grey levels from 0 to 255.

Multidirectional Hillshade

The same idea lit from eight or more directions at once. It removes the dark faces a single light leaves behind, which is the usual complaint about a plain hillshade in complex terrain. Preferred for publication quality maps.

It takes the same altitude and z factor, plus a full 360 mode that spreads the light sources all around rather than over a half circle.

Hypsometrically Tinted Hillshade

A finished Swiss style rendering in one run: multidirectional shading blended with colours that follow elevation, and an optional atmospheric haze. Use it when you want a beautiful terrain background without building a colour ramp yourself.

Feature Preserving Smoothing

The tool to reach for when your DEM is noisy but you do not want to lose its edges. An ordinary blur would round off cliffs and terraces along with the noise. This one works on surface normals, so it flattens the grain while keeping breaks in slope intact.

Run it before computing slope or curvature on a LiDAR derived model, where the raw surface is too noisy for a readable derivative.

Fill Missing Data and Dem Void Filling

Two ways to repair holes. Fill Missing Data interpolates NoData gaps from the valid cells around them, which is right for small holes. Dem Void Filling merges a second surface into the gaps, adjusting it so the join is seamless, which is right for the large voids of radar based models in steep terrain.

Remove Off Terrain Objects

Takes a surface model that includes buildings and trees and returns something closer to bare ground, by detecting steep sided objects and interpolating the terrain under them. Useful when the only elevation data you have is a DSM.

All the tools

Tool	What it does
Assess Route	Splits route lines into segments and reports terrain metrics for each, from a DEM.
Breakline Mapping	Extracts breaklines by thresholding curvedness and vectorising the thinned result.
Convergence Index	Measures whether local aspect converges or diverges, marking valleys and ridges without full flow routing.
Dem Void Filling	Fills large voids using a secondary surface, matched to the original at the edges.
Deviation From Mean Elevation	Local topographic z-score: how far each cell sits from its neighbourhood mean, in standard deviations.
Difference From Mean Elevation	The same comparison expressed in elevation units rather than standard deviations.
Directional Relief	Relief along a chosen azimuth, by ray tracing the surface.
Elev Above Pit	Height of each cell above the nearest downslope pit or edge sink.
Elev Above Pit Dist	Compatibility alias for Elev Above Pit.
Elevation Percentile	Rank of each cell within its neighbourhood, from 0 to 100. Low is a valley, high is a ridge, independent of absolute altitude.
Embankment Mapping	Maps road and rail embankments from a DEM and a road network, optionally removing them from the surface.
Exposure Towards Wind Flux	Terrain exposure to a dominant wind direction, accounting for upwind shielding.
Feature Preserving Smoothing	Smooths surface noise while keeping breaks in slope, using surface normals.
Feature Preserving Smoothing Multiscale	The same, applied from coarse to fine scales for stronger noise removal.
Fetch Analysis	Upwind distance to the first obstacle along a given azimuth.
Fill Missing Data	Fills NoData gaps by inverse distance weighting from the valid cells around them.
Find Ridges	Marks ridge and peak cells, optionally thinned to single cell lines.
Hillshade	Shaded relief from one light source, with azimuth and altitude you choose.
Hypsometrically Tinted Hillshade	Swiss style rendering blending multidirectional shading with elevation tinting and optional haze.
Local Hypsometric Analysis	Minimum local hypsometric integral across a range of neighbourhood scales.
Low Points On Headwater Divides	Finds the low passes along divides between neighbouring headwater basins.
Map Off Terrain Objects	Detects buildings, trees and other objects sitting on the terrain in a surface model.
Max Downslope Elev Change	Largest elevation drop from each cell to a lower neighbour.
Max Upslope Elev Change	Largest elevation gain from each cell to a higher neighbour.
Min Downslope Elev Change	Smallest non negative drop from each cell to a neighbour.
Multidirectional Hillshade	Shaded relief from eight or more light sources, without the dark faces of a single light.
Num Downslope Neighbours	How many of the eight neighbours are lower than each cell.
Num Upslope Neighbours	How many of the eight neighbours are higher than each cell.
Profile	Elevation profile along one or more lines, as an HTML plot.
Remove Off Terrain Objects	Removes buildings and vegetation from a surface model and interpolates the ground beneath.
Ridge And Valley Vectors	Extracts ridge and valley centrelines as vector lines.
Slope Vs Aspect Plot	Radial plot of slope against aspect, as HTML.
Slope Vs Elev Plot	Chart of slope against elevation, as HTML.
Smooth Vegetation Residual	Removes the residual roughness canopy leaves in a terrain model.
Surface Area Ratio	Ratio of true 3D surface area to flat area. Above 1 is rough, near 1 is flat.
Topographic Hachures	Draws hachure lines following the slope, the classic hand drawn relief style.

Notes

Reports are downloads. Profile, Slope Vs Aspect Plot and Slope Vs Elev Plot produce HTML documents, which are downloaded rather than added to the map.

Order matters. Repair first, then smooth, then derive. Computing slope on a model still full of voids gives artefacts around every hole.