Lab Exercise #5: Working with CAD Data in GIS

GEOG 300: Intermediate GIS

The main objective of this lab exercise is to examine the CAD data viewing capabilities in

ArcCatalog and ArcMap.

Introduction

The CAD data model is used by engineering and surveying professionals in many industries

(transportation, civil engineering, construction, mining, and emergency management). CAD maps

are often created in local coordinates (screen coordinates or “paper inches”) rather than the

geographic coordinates which are more useful for GIS. Each CAD drawing file (.dwg extension)

contains several named or numbered layers that can be viewed and symbolized individually.

In this week’s exercise, you will work with CAD data that was provided by the Moab City

Planning Department, Moab, Utah, and a DEM from the USGS. The data used in the exercise

consists of a CAD drawing file, shapefiles, digital elevation model data, and a CAD world file. This

exercise has been modified for use in ArcGIS v.9.3. from a 2000 ArcUser article entitled “Modeling

CAD Data in ArcView GIS”.

I. Viewing CAD Data in ArcCatalog and ArcMap

1. The data sets for this exercise have been downloaded from ESRI’s ArcUser magazine’s web site.

Copy the lab5 folder from O:\GIS\geog300 to your M:\geog300 folder.

2. Start ArcCatalog, and navigate to M:\geog300\lab5\moab_data. Use the

ArcCatalog Preview tab to view each map. There are eight CAD related

files in the moab_data folder as shown to the right. The Moabtopo.dwg

file is a CAD dataset. CAD datasets can contain point, line, polygon,

multipatch (contains 3D geometry information), and annotation (text label)

feature classes. Click on the + sign to expand the contents of the

Moabtopo.dwg dataset so that you can see these feature classes listed.

Each feature class contains all of the individual features and their

attributes. CAD drawing files contain all features and annotation within the

single CAD file, and features are drawn using the symbology defined

within the CAD file. You cannot change the symbology of CAD drawing

files, but you can change symbology for CAD datasets. Beneath

Moabtopo.dwg, the Moab1158.dem layer consists of the 30-meter

resolution DEM for the Moab 7½’ quad from the USGS. This data will be

processed and symbolized in later steps. The six Moab shapefiles include

bike trails, GNIS points (remember GNIS?), jeep trails, rivers, roads, and

section lines. You will use the DEM and the roads and rivers shapefiles in a later step.

3. Start ArcMap and click on the Add Data button. Navigate to the Moabtopo.dwg CAD dataset,

select it, and click on the Add button in the Add Data dialog box. The five feature classes are

displayed in the table of contents: annotation, point, polyline, polygon, and multipatch. Currently the

coordinate system is undefined – that will be changed in a later step.

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Download Lab Exercise #5: Working with CAD Data in GIS | GEOG 250 and more Lab Reports Geography in PDF only on Docsity!

GEOG 300: Intermediate GIS

The main objective of this lab exercise is to examine the CAD data viewing capabilities in

ArcCatalog and ArcMap.

Introduction

The CAD data model is used by engineering and surveying professionals in many industries

(transportation, civil engineering, construction, mining, and emergency management). CAD maps

are often created in local coordinates (screen coordinates or “paper inches”) rather than the

geographic coordinates which are more useful for GIS. Each CAD drawing file (.dwg extension)

contains several named or numbered layers that can be viewed and symbolized individually.

In this week’s exercise, you will work with CAD data that was provided by the Moab City

Planning Department, Moab, Utah, and a DEM from the USGS. The data used in the exercise

consists of a CAD drawing file, shapefiles, digital elevation model data, and a CAD world file. This

exercise has been modified for use in ArcGIS v.9.3. from a 2000 ArcUser article entitled “Modeling

CAD Data in ArcView GIS”.

I. Viewing CAD Data in ArcCatalog and ArcMap

The data sets for this exercise have been downloaded from ESRI’s ArcUser magazine’s web site. Copy the lab5 folder from O:\GIS\geog300 to your M:\geog300 folder.
Start ArcCatalog, and navigate to M:\geog300\lab5\moab_data. Use the ArcCatalog Preview tab to view each map. There are eight CAD related files in the moab_data folder as shown to the right. The Moabtopo.dwg file is a CAD dataset. CAD datasets can contain point, line, polygon, multipatch (contains 3D geometry information), and annotation (text label) feature classes. Click on the + sign to expand the contents of the Moabtopo.dwg dataset so that you can see these feature classes listed. Each feature class contains all of the individual features and their attributes. CAD drawing files contain all features and annotation within the single CAD file, and features are drawn using the symbology defined within the CAD file. You cannot change the symbology of CAD drawing files, but you can change symbology for CAD datasets. Beneath Moabtopo.dwg , the Moab1158.dem layer consists of the 30-meter resolution DEM for the Moab 7½’ quad from the USGS. This data will be processed and symbolized in later steps. The six Moab shapefiles include bike trails, GNIS points (remember GNIS?), jeep trails, rivers, roads, and section lines. You will use the DEM and the roads and rivers shapefiles in a later step.
Start ArcMap and click on the Add Data button. Navigate to the Moabtopo.dwg CAD dataset, select it, and click on the Add button in the Add Data dialog box. The five feature classes are displayed in the table of contents: annotation, point, polyline, polygon, and multipatch. Currently the coordinate system is undefined – that will be changed in a later step.

II. Examining CAD Attributes and Filtering CAD Data

The CAD datasets consist of a limited number of attributes. Open the attribute table for the Moabtopo.dwg Polyline layer. The most useful attribute is Layer , and it consists of the name of each polyline layer type. As you scroll down on the table, notice that some of the polylines define layers that you might automatically assume to be points (e.g., SPOT-ELEV for spot elevations) and polygons (e.g., BUILDINGS ). The Moab city engineers have duplicated some of their features, and spot elevations are represented by both polylines and point symbols, while buildings have both polyline and polygon symbols. Close the attribute table when you are finished with it.
CAD datasets contain spatial entities that are separated into different groups or layers (map features). Open the Moabtopo.dwg Polyline Layer Properties dialog box. Click on the Drawing Layers tab to view the different layers and whether they are visible (checkmark) or invisible (no checkmark). The Moab city engineers created this CAD dataset so that all layers were initially visible (note the check marks in the boxes to the left of the layer names). If you were to view the drawing layers for the other feature classes (annotation, point, polygon, and multipatch) you would see that they consist of the same layers and that they are all visible. Close the Properties dialog box.
Click on the Add Data button, navigate to M:\geog300\lab5\moab_data , double click on the Moabtopo.dwg CAD dataset (same dataset as before), and add the polyline feature. You now have two layers named Moabtopo.dwg Polyline listed in the Table of Contents. a. Open the Layer Properties dialog box for the topmost Moabtopo.dwg Polyline layer listed in the Table of Contents. b. Under the General tab, change the layer name to contours. Click on the Drawing Layers tab and make only these index and intermediate contour line layers visible – IND-CONT-DEP , IND-CONTOUR , IND- DTICK , INT-CONT-DEP , and INT-CONTOUR (note: IND means index contour, INT means intermediate contour, DEP means depression, and IND-DTICK means index depression contour tick marks or hachures (see diagram to the left). Click on the Apply button. Click on the Symbology tab, choose Unique Values under Categories, and change the value field to Layer. Click on the Add All Values button to see all of the contour layers. Remove the checkmark from . Change the line symbol for the contour lines to those symbols reserved for Index and Intermediate topographic contours. Use a 0.8 line width for the Index contours and a 0.2 line width for the Intermediate contours. For the hachures, use the index topographic contours symbol, but change the width to 0.2. Click on the OK button to apply these changes. c. Open the Layer Properties dialog box for the remaining Moabtopo.dwg Polyline layer. Change the layer name to polylines. Disable these drawing layers: the four contour lines (see step 3b above for their names), and the IND-DTICK , AREA-PAVED , BUILDING , and HTXT layers. The other layers should remain visible. Click on the Apply button. Change the polylines’ symbology so that all of the remaining polyline layers (CULVERT, CURB, DITCH, etc.) are symbolized by Layer name with a different color. Use the first color ramp available in the dropdown listing (“Basic Random”). Remove the checkmark from . Click on the OK button to apply these symbology changes. d. For the Moabtopo.dwg Polygon layer, change the layer name to polygons. Disable all of the layers except AREA-PAVED and BUILDING. In the Symbology tab, choose the Layer values field, and only symbolize the AREA-PAVED and BUILDING polygons. Fill these polygons with unique colors – your choice. Remove the checkmark. e. Turn the Moabtopo.dwg Annotation , Point , and MultiPatch layers off in the Table of Contents.
Have you saved the map document yet? No??? Yikes!!! Well, now is the time to do it. Save the map document file as Moab.mxd , and save it to your M:\geog300\lab5 folder.

III. CAD Data Transformations

According to the ArcUser magazine, surveying in the Moab Valley for many years was tied to a local coordinate system registered in feet despite the fact that some Grand County surveyors often created data in metric coordinates projected in UTM NAD27, Zone 12. You can use a CAD world file to transform the CAD data from local coordinates to UTM. The world file is included in your moab_data folder ( wldfile1.wld ). For more information on world files and CAD data, see page 5.

These little lines are hachures.

V. Creating the Layout

You will be printing this map on the color laser printer in BH 570. In the layout view, create a landscape-oriented layout that shows (1) the DEM/hillshade with CAD layers and the two shapefiles on the left side of the layout page (zoomed out to the full extent of moabdem ), and (2) the CAD layers without the DEM/hillshade/shapefiles on the right side of the page (zoomed in to the CAD layers). You will need to use two data frames to do this, and the easiest way to get two is to move the current data frame to the left side of the layout page (stay within the page border), copy this data frame, and paste a copy of this data frame in the right half of the layout page. Make sure you choose the correct map layers for this new data frame, and that within this second data frame, you have zoomed in to the CAD layers.
Rotate both data frames so that the west and east borders of the maps align with the data frame borders. The UTM grid declination (and rotation angle) for the Moab quad is 54’. That’s 54/60th^ of a degree.
Add a main title that succinctly describes both maps in a few words of text, two subtitles for each data frame, scale bars for each data frame, north arrows, and a map border (“neatline”) surrounding everything and just within the page edge borders. Also add a single Data Sources statement indicating the sources for the vector, CAD, and raster data sets. The main title and data sources statement should be centered and aligned to the page edge borders, and the two subtitles and scale bars should be centered and aligned to their respective data frame borders. Don’t worry about a legend for the left map as the map title and symbols/labels are sufficient, but do add a legend for the zoomed-in CAD data layers map in the right map. Create a legend for the contours, polyline, and polygon layers only. Edit the individual components of the legend as described below. a. Create a one-column legend. b. Make sure you have removed all of the text from the Table of Contents. c. In the Table of Contents for each of the three visible layers, click, pause, then click again on the word Layer and delete it. This word is redundant for all three layers. d. Edit the labels for the Contour Lines layers from within the Layer Properties dialog box. Group the IND- contour line layers together, and then rename the grouped symbols to index. Group and then rename the INT- contour line layers to intermediate. Rename the IND-DTICK to hachures. e. For the Polylines layer, change SPOT-ELEV to SPOT ELEVATION. Leave the rest of the Polylines layers and Polygons layers set to their default names.

Position the Legend in an unused portion of the map.

Print the map on the color laser printer in Berndt 570.
Save this ArcMap document one last time, and quit for the week!

control points

Points you establish on a paper map whose coordinates represent known ground points or specific locations. Control points are used to register a paper map before you begin digitizing features on it using a digitizer , or transform a digital map (such a CAD dataset) to geographic coordinates.

The wldfile1.wld world file (shown above) contains coordinate pairs for two control points, so ArcMap will apply a two-point transformation to the CAD datasets.

Lab Exercise #5: Working with CAD Data in GIS | GEOG 250, Lab Reports of Geography

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Download Lab Exercise #5: Working with CAD Data in GIS | GEOG 250 and more Lab Reports Geography in PDF only on Docsity!

GEOG 300: Intermediate GIS