New Media in Landscape Architecture:

Advanced GIS

- 3D Analysis -

Version 10.2, English

ANHALT UNIVERSITY OF APPLIED SCIENCES Hochschule Anhalt

Author:

Dr. Matthias Pietsch

Tutorial-Version: 2015

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3D Analysis

Task

GIS offers capabilities for creating, visualizing and analyzing GIS data in a three-dimensional context.

In ArcGIS it’s possible to analyze different types of surfaces (TIN or raster surfaces). Depending on

the tools and the used data formats you use the results will be represented as raster or vector da-

tasets.

For two planning scenarios for windmills should be compared using viewshed-analysis. Based on the

results the planning should be improved by changing position or height of the objects or by adding

some landscape elements. The results should be presented in 3D using ArcScene.

Data

There are two scenarios for windmills as shape-files (standpkt1.shp and standpkt2.shp) and a poly-

gonshape with the existing landuse types from the environmental agency (kcir). The height of specific

landuse types have been added in the attribute table (field: height).

Used functions

Create TIN

Calculating Surface Aspect

Convert TIN to raster

Recalculate DEM

Surface analysis (e.g. viewshed, line of sight)

Compare two planning scenarios

Visualize the results in 3D using ArcScene

How to do this

1. Prepare your data frame

Start the program, create a new map document and add some data.

Windows Double-click the ArcMap icon on your desktop or click the

Start button and point to Programs - ArcGIS - ArcMap to

launch ArcMap.

ArcMap dialog

Blank Map

Create a new empty document.

Set the properties of your new empty data frame.

2. Add layer

Standard toolbar

Add data

Add fcir from folder …\exercise4\shape and symbolize the

data based on the field K.

Add the layer standpkt1.shp and standpkt2.shp from folder

…\exercise4\shape and symbolize the points in different

colors.

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3. Create TIN

Surface analysis are calculated based on digital elevation

models (TINs or raster surface). They can be calculated

using different data formats. In our example we use a dbf-file

with X-, Y- and Z-values.

Standard Toolbar

Add Data

Add the layer …\tables\24AA1_2.dbf. For the interpolation

process it’s necessary to create a point layer based on the

coordinates in the dbase-file.

Display XY Data Rightclick on the layer dbf and open the Display XY Data

window. Select X for X-Field, Y for Y-Field and Z for Z-Field.

Select Germany_Zone_4 as the Coordinate System of Input

Coordinates using the Edit … Button. Create an Event layer

by clicking OK. Now it’s possible to create a TIN using the

point layer.

3D Analyst Tools

Data Management

TIN

Create TIN

Check, if the Extension 3D Analyst is activated. Open the

Create TIN tool to interpolate a TIN. Save the result in

…exercise4\tin. Select Germany_Zone_4 as Coordinate

System and use the 24AA1_2 Events layer as Input Feature

Class. Change the Height Field to Z.

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Layer 24AA1_2 Events

Remove the layer.

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Triangulated irregular networks (TIN) can be displayed by aspect.

TOC

Layer TIN

Right-click the TIN in the table of contents and select Prop-

erties. Click the Symbology tab. Uncheck Elevation and click

Add. Select Face aspect with graduated color ramp and click

Add. Click Dismiss in the Add Renderer Window. Click OK

in the Layer Properties Window.

The different categories will be displayed and labeled as

standardized color-coded polygons.

4. Calculate Surface Aspect

If aspect is needed as one criteria for following analysis it must be calculated using surface

tools. Surface aspect calculates the aspect, or direction of the steepest downhill slope, of

each triangle in a TIN or terrain dataset and writes the output as a polygon feature class.

3D Analyst Tools

Triangulated Surface

Surface Aspect

Open the Surface Aspect Tool to calculate the aspect of

each triangle in the TIN. Save the result in

…\exercise4\shape\aspect.shp.

Each surface triangle's aspect is determined in units of

degrees, then assigned an aspect code based on direction

of its slope. Open the attribute table of the layer aspect.shp.

In the field AspectCode the following classification scheme

is used:

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Code

Slope

Direction

Slope Angle

Range

-1 Flat No Slope

1 North 0–22.5

2 Northeast 22.5–45

3 East 45–135

4 Southeast 135–180

5 South 180–225

6 Southwest 225–270

7 West 270–315

8 Northwest 315–337.5

9 North 337.5–360

5. Convert TIN to Raster

ArcToolbox

3D Analyst Tools

Conversion

From TIN

TIN to Raster

For visibility analysis raster datasets are needed. Therefore

you have to convert the TIN to a raster file. Open the tool

TIN to Raster. Select the TIN as Input TIN. Save the output

raster in …\exercise4\grid\height. The Output Data Type

should be FLOAT. Select as Method LINEAR and as Sam-

pling Distance CELLSIZE 10. Click OK.

6. Recalculate DEM adding existing height of specific land use types

The attribute table of the layer fcir has a field height. The given value represents the height

of specific land use types. The raster dataset height should be recalculated using these

values. Therefore the layer must be converted from vector to raster.

ArcToolbox

Conversion Tools

To Raster

Polygon to Raster

Open the tool Polygon to Raster. Select layer fcir polygon as

Input Features. The Value field is Height. Save the Output

Raster Dataset …\exercise4\grid\landuse. The Cellsize is

10.

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ArcToolbox

Spatial Analyst Tools

Map Algebra

Raster Calculator

To add the height of the specific land use types to the layer

height the Extension Spatial Analyst is needed. Please take

care that the extension is activated!

Open the tool Raster Calculator. Add “landuse” + “height” as

Map Algebra expression and save the output raster in

…\exercise4\grid\dom.

7. Viewshed Analysis

In the next step the raster surface locations visible to the observer features of the layers

standpkt1.shp and standpkt2.shp representing two possible scenarios for windmills should

be determined. Therefore it’s necessary to add the height for each object and to calculate

visibility.

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Layer standpkt1.shp

Open the attribute table. Add a field. Name OFFSETA, Type

Short Integer and Precision 3. Add for each object the fol-

lowing height:

WEA1 = 150

WEA2 = 170

WEA3 = 160

WEA4 = 150

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ArcToolbox

Spatial Analyst Tools

Surface

Viewshed

Open the Viewshed tool. Select as Input raster dom. The

Input point or polyline observer features is standpkt1.shp.

Save the Output raster in …\exercise4\grid\viewshed1.

In the layer viewshed1 all cells with a value of 0 are not

visible, all cells with values from 1 to 4 are visible.

Repeat all steps for the layer standpkt2.shp and

compare the results. Calculate the area in sqm that is

visible for standpkt1.shp and standpkt2.shp. Make some

changes (e.g. height of objects, position of objects, add

some landscape elements) and compare again.

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3D visualization using ArcScene

ArcScene is a 3D viewer that is well suited to generating perspective scenes that allow you to navi-gate and interact with your 3D feature and raster data. Based on OpenGL, ArcScene supports com-plex 3D line symbology and texture mapping as well as surface creation and display of TINs. All data is loaded into memory, which allows for relatively fast navigation, pan, and zoom functionality. Vector features are rendered as vectors, and raster data is either downsampled or configured into a fixed number of rows/columns you set.

In this example, you should use ArcScene to visualize the results of your viewshed analysis and to create 3D features based on a given surface.

Used Functions

Add layers

Visualize layers in 3D

Create 3D layers

How to do this

1. Create a 3D Scene

Prepare your Scene Double click ArcScene icon on your desktop or open it from

start windows, programs click ArcScene

2. Add layers

Standard tool bar

Add layer

Add from …\exercise4\ the layer tin. Add from

…\exercise4\grid the layer viewshed1 and from exer-

cise4\shape the layer fcir..

Menu

Scene Properties

Right click on Scene Layers to open the Scene Properties

window. In the General tab it’s possible to change the back-

ground color and to define the Vertical Exaggeration. Some-

times it’s helpful to use the button Calculate From Extent.

Vertical exaggeration can be used to emphasize subtle

changes in a surface. This can be useful in creating visuali-

zations of terrain where the horizontal extent of the surface is

significantly greater than the amount of vertical change in the

surface. Select 2 as vertical exaggeration and click OK.

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3. Visualize Surface

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Layer TIN

Right click on the layer tin and open the Layer properties

window. Select the Symbology tab. If elevation is not availa-

ble click on add button and select face elevation with gradu-

ated color ramp.

4. Visualize Layer

Viewshed1

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Layer viewshed1

Right click on the layer viewshed1 and open the Layer proper-

ties window. Select the Base Heights tab. Select Floating on a

custom surface and select tin this will drape the raster layer on

the tin surface.

Select the Symbology tab. Change the colours to:

0 = red = not visible

1 to 4 = green = visible.

Click OK.

5. Create 3D layers

For a specific project we want to create a cycling route on the existing surface as a 3D feature.

Therefore it’s necessary to create a new layer (e.g. Shapefile, File Geodatabase) in ArcCatalog.

Open ArcCatalog and create a File Geodatabase in

….\exercise4. Rename the New File Geodatabase.gdb in

touristic_infrastructure.gdb. Right click on touris-

tic_infrastructure.gdb and select New Feature Class. The

Name is bicycleroute, the Type is Line Features and check all

Geometry Properties.

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Click Next. Select the Coordinate System Germany Zone 4

and click Next. Select as vertical coordinate system from the

folder Europe DHHN92 and click Next. Click next twice. If you

want to add some fields in the File Geodatabase you can add

the field names and the data types.

Click Finish.

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ArcScene

Standard tool bar

Add layer

Add the feature class bycicleroute from

…\exercise4\touristic_infrastructure.gdb.

Right click on the layer bycicleroutes and open the Layer

Properties window. Select the tab Base Heights. Select

floating on a custom surface and no feature based height.

To create 3D features open the 3D Editor toolbar. In the Main

Menu Customize select Toolbars and open the 3D Editor

Toolbar.

To digitize features select from the 3D Editor Toolbar the

Start Editing Tool, select bycicleroutes and click OK. fIn the

Create Features window select bycicleroutes and from the

Construction Tools Line.

Now digitize some features on the tin layer. If you have

finished stop the digitizing process by using the Stop Editing

Tool. The digitized features are now 3D objects.

6. Extrude layers You can extrude 2D features into 3D objects of different

heights by using feature attributes as the extrusion height.

Extrusion is a layer property setting for the feature layer and

requires you have a base height already applied for the

feature layer in order for extrusion to apply. By combining

base heights and extrusion properties, you can create a more

realistic 3D view, without ever requiring 3D features.

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TOC

Layer fcir

Right click, open the Layer Properties window and select the

Extrusion tab. Check the box. Click the Expression Builder

button. The height of some land use types are in the field

height in the attribute table of the layer fcir. Select in the

Expression Builder window the field [Height] and click OK.

Select from the dropdown list the extrusion method “adding it

to each feature’s base height”. To drape the layer on the

existing surface select the Base Heights tab. Click the Float-

ing on a custom surface, select the layer tin and click OK.

The result can be exported as a 2D (e.g. pdf, jpg, tif) or a 3D

(VRML) scene.