Foundations Of Geographic Information Systems Assignment Package
GIS 5103 – Week 8 Exercise – 3D GIS – November 4, 2019
The objective of this week’s assignment is to expose you to the 3D GIS data, programs, and tools. The analysis will be limited as the processing and rendering requirements are very large and will take much too long to do on the NEU server. The exercise will contain information on how to create 3D data from raster files, how and where to download pre-made 3D data files, how to navigate in a 3D environment, and where to find many of the common 3D analysis tools.
(Rather than do the analysis yourselves, the 3D analyst tools will be demonstrated.)
Necessary Files:
MA Elevation Raster – MASSGIS - https://docs.digital.mass.gov/dataset/massgis-data-digital-elevation-model-15000
Cambridge Roads Shapefile - https://www.cambridgema.gov/GIS/gisdatadictionary/Basemap
Cambridge Buildings Multipatch - https://www.cambridgema.gov/GIS/3D/3ddata/3ddatadownloadmap
1. Download the zipfiles from the websites and save them to classfolder.
a. (as a failsafe the files will be saved under Data in the classfolder)
2. Open ArcMap and open the customize tab, go to extensions and make sure the 3D analyst extension is checked off.
3. Add the ( img_elev5k_i ) Raster File, which is also a DEM.
4. Add the draw tool.
5. Use the draw tool to create a box around the city of Boston, including Cambridge
a. (the smaller the square the better)
6. Once the square is created on top of the DEM, right click the raster layer, click data, then export data.
7. Once the options window opens, make sure the selected graphics option is chosen (clipping). Change the name of the clipped DEM to something else.
8. Once you have finished that step, we will get something that looks like this. Do not worry you can change the stretch by going right clicking the new layer, going into properties, then going to the symbology tab.
9. Now that we have a clipped DEM to our area of interest, we can project the raster to a projected coordinate system. Use the search tool to find Project Raster tool. Fill in the first two options then in the output coordinate system locate UTM, NAD 1983, 19N (specific to the MA / East coast area)
10. You can check in the properties tab of the new raster to make sure it was properly projected.
11. Once we have our clipped and projected raster, we can change it to a TIN.
a. Using the search tool, find the Raster to TIN tool.
b. Specify the correct raster file, change the name and save location, and change the Z tolerance to 1.
12. Now that you have created a TIN, you can open ArcScene and open the TIN there.
a. Opening a TIN in ArcMap is slow and not visually appealing.
13. Now that we have our TIN, we are going to add our 3D building shapefile from Cambridge.
a. At first nothing may appear because it is below the TIN layer.
b. First go to the TIN layer properties, then navigate to the base heights tab.
c. Change the custom number to 1.1
d. Then go back to your 3D buildings layer and navigate to the base heights tab there. Make sure to check off the “Floating on custom surface” button.
e. Now add the BaseMap_Roads layer to ArcScene.
i. Again, make sure the “floating on custom surface” button is checked.
f. Go back to the TIN layer and change the custom Base height back to 1.
g. If don’t correctly you should have something that looks like this.
If you want to add any additional layers from the Cambridge website, you will have to change the Bae height on the TIN to .5 and check off “Floating on custom surface” for each additional data layer.
Questions:
1. Why did we have to re-project the DEM to turn it into a TIN?
2. Why did we change the Z tolerance on the TIN to 1?
3. Is it realistic to have the roads and any other additional layers “floating” on top of the TIN layer?
4. Make an exaggerated elevation map by only having the TIN layer displayed.
a. Change the “factor to convert layer elevation values” custom number to something greater than 1.
5. Additionally, Explore the 3D analyst Tools and:
a. Create a contour lines layer
b. Create a Slope layer
c. Create an aspect layer
6. Additionally, explore the navigate, fly, center on target and zoom to target buttons.