3D Analyst

Components

• ArcScene– Is where 3D Analyst is located– Visualization and Some Analysis

• ArcGlobe– Like Google Earth – google’s is better

• ArcMap - does NOT display 3D!• ArcCatalog – can preview in 3D

3D Data

• Has a Z value• Elevation is most common Z value• But can also represent

– Pollution levels– Noise levels– Precipitation …. Etc.

Kinds of 3D data structures

• DEM raster

• TIN (Triangulated Irregular Network)

TIN

• Every 3 points of Z are connected to make a Triangle w/ Area, Slope, and Aspect.

3D view

• Open ArcScene• Load DEM or TIN• Raster will be flat!• Set base height• Set vertical exaggeration • Illumination of DEM

Navigation tools different

• General nav tool

• Zoom tool Fly tool

• Guess what?

• Expand field of view

• Narrow Field of View

Done while we go through these

demos

Vertical Exaggeration

• Why?– used to emphasize small changes– bring z-units into proportion with x,y

units

• It is a only visual effect that does NOT affect analysis

Illumination

• Every Scene has a light source – the sun• Thus different parts of the scene are

illuminated differently• The sun’s position is described by…

– The sun’s azimuth is measured from 0 (north) to 360 (north) ccw. (315 (NW) is default)

– The sun’s altitude (0-90) is its height above the horizion.

Layer Properties

• Base Heights – establishes the elevations of surface

locations and features.

• Extrusions – tells 3D Analyst how high a feature rises

above the ground or extends below it.

Base Heights• Elevation values that are used to

display a layer in 3D. • These values can come from various

places.– layer:

• the node elevations in a TIN, • the cell values in a raster, • the z-values in a 3D feature layer, • or the elevation attribute values for a 2D

feature layer.

Rendering

• In layer’s properties• Scene Layer properties

Extrusions

• three-dimensional extension of features. – An extruded point a line;– an extruded line a wall; – an extruded polygon a chunk.

• There are many methods used to do this

Surface Calculations

• Slope• Aspect• Hillshade• Contours• (Reclassification) • Pretty much the same as ArcGIS

but tools in 3D Analyst Tools

Adding 2D data

• Turning on in TOC does not do much – maybe can’t even see it!

• Have to set the layer’s elevations– Layer properties/Base Heights from

DEM