Creating Shaded Relief Images Using Aerial Photos, DEMs and ArcMap.

Creating Shaded Relief Images

Using Aerial Photos, DEMs and ArcMap

Color aerial photo with .5 m resolution

DEM with approx 10 m resolution

Hillshade created from DEM with default lighting at 315° azimuth, 45° altitude

Hillshade created from DEM with lighting at 170° azimuth, 40° altitude to approx match shadows on aerial photo

Hillshade with 315° lighting angle Hillshade with 170° lighting angle

Hillshade lit from 315°Naturally lit orthophoto

conflicting shadows

Naturally lit orthophoto Hillshade lit from 170°

complimentary shadows

Combined orthophoto and semi-transparent hillshadeusing hillshade constructed with 315° lighting angle

Combined orthophoto and semi-transparent hillshadeusing hillshade constructed with 170° lighting angle

Inset of shaded relief orthophoto using 315° lighting angle

Creating 3D Scenes

Using Aerial Photograph, DEM and ArcScene

Aerial photo added to ArcScene, default view

Photo rotated and viewed edge on confirms 2D representation

In the Layer Properties box for the air photo, click on the Base Heights tab and change the setting to obtain heights from surface and browse to the correct elevation file.

The airphoto is now draped over the elevation surface as seen in this edge-on view

The default view now shows a true 3D representation of the scene

The Layer Properties Rendering tab is the key to getting good-looking images in ArcScene.

Check the Shade areal features … box (this is unchecked by default).Change the Quality to High (this is set to a midpoint position by default).

The high-quality render takes up lots of video memory, so, if you’re running on an older PC or one without a high end video card, your image may break up as it is rotated in ArcScene.

The Shade areal features… comes into play on the next step, which will not work if this is not checked.

Scene Properties Illumination governs the scene light position.This light position, and checking the “shade layers relative to scene light” box in the layers properties, governs how shadows and highlights play across the scene as it is rotated, enhancing or disrupting the 3D effect.

The Sun Position and Elevation

http://www.srrb.noaa.gov/highlights/sunrise/azel.html

Lat/Long read from ArcMap screen

Date and time from meta data

315°

170°

Zooming in for a closer look Scene light set to 315°: conflicting shadows do not match those in the air photo

Scene light set to 170°: No

conflicting shadows with those in the air photo

315° lighting angle

170° lighting angle

High quality render setting

Medium quality render setting

Low quality render setting

Render Quality Comparison High, Medium, Low (L to R)