Goals and background
- Access and download NTS (GeoGratis) data and use for 3D visualization
- Understand data processing to achieve goals
- This assumes students are already familiar with NTS and DEM.
- Download data from GeoGratis
- Project this downloaded data into UTM NAD 83 Zone 10 N
- Clip out a study area from the projected data set
- Create a 2D map in ArcMap with the clipped data set
- Exports the styling of each layer from the 2D map (can be used in ArcScene for instance)
- Export a map or the styled raster layers to a Tiff file from ArcMap
- Test the layers in ArcScene (including the exported map)
- Export a second map from ArcMap with all vector layers included
- Export the clipped (study area) DEM as an ASCII type file
- Create a 3D scene in Terrain Bender using the ASCII DEM as a surface, with an overlay of the exported map (the map with vectors included)
Background to the files you will be downloading and preparing:
The data for this lab will be acquired from the federal government on the GeoGratis web site. We are using raster Digital Elevation Model data. The DEM we are using for the lab is in British Columbia, but DEM data is available for all of Canada. It is not well know, but the DEM information we are using is actually Terrain Resource Information Management data (TRIM) created by the BC Government. The data is at 25 metres from the BC government normally, but we will not be concerning ourselves with resolution for this mapping project
The vector data we are using will be from GeoGratis as well. We have used these data in previous labs. Instead of layering the vector data we are actually going to effectively rasterize the vectors and use them in a 3D map.
1. Downloading data and getting it set up in ArcMap :
Getting data from GeoGratis
- Go to http://geogratis.gc.ca/site/eng/extraction/
- Use the search panel and put Quesnel Lake –> first option Quesnel Lake in the Cariboo
- Follow the options in the images below (although all we really need for the lab are the Hydro and Elevation layers
- Put in your email in submit request panel
- You will get an 2 emails to download the data (one for the request and one for obtaining the data)
- Download to your lab8 directory
Manage the data and set it up in ArcMap
Once the data is downloaded,
- right click in the zip file –> click OK for the windows security panel –> Extract All
- Open ArcMap and load the DEM layer from the folder ending in tif (created by unzipping the file)
- Add the following shape files from the folder ending in shp (the shape files may be numbered as well (i.e contour_1.shp)
- You will get an 2 emails to download the data (one for the request and one for obtaining the data)
- Download to your lab8 directory
Projecting and clipping the data
We need to get the data we have just downloaded into a nice projection such as UTM Zone 10.
- Arctoolbox –> Data Management tools –> Projections and transformations –> Raster –> Project Raster
- Input is DEM
- Output a new DEM (i.e. quesnel_lake_dem.tif)
- Coordinate system –> projected coordinate systems –> UTM –> NAD 83 –> Zone 10 N
(HINT: the first time you navigate to UTM zone 10N, highlight it (click once), then click the add to favorites button (star) to make selection quicker next time
- Resampling technique is cubic
- We will leave the output size of the pixels for the new layer as the default (18… metres). Aside: Often we would set output pixel size to 25×25 metres (type it in the x and y windows) to match existing datasets
- Project the downloaded vector layers (water bodies, roads and contours) into UTM as well
- Arctoolbox –> Data Management tools –> Projections and transformations –> Project (similar to the raster projection you did above)
- User suitable names (i.e. lakes, roads and contours)
Clipping out a study area
Start ArcCatalog and navigate to your lab8 folder. Once there create a new polygon shapefile called clip_area.shp. You did this in lab3 “Data Input and Update” (part 5E)
Start a new map in ArcMap (File –> new) without saving the map you were just working on
- Load the DEM and the Lakes, Roads and Contours into this new map (the UTM versions of the data), but only turn on the DEM layer
- Load the newly created empty clip_area.shp file into the map as well
- Start the editor to add a rectangle to the clip_area.shp file (again you did this in Lab 3)
-Open the Editor tool bar and start the editing (click the Editor pull down panel –.>start editing)
-Click the Editor pull down –> Editing Windows –> Create Features
-Click on the clip_area.shp layer to edit
-Choose the Rectangle Tool in the add feature window
- Draw a rectangle that fits inside the DEM and is perpendicular to the data frame (take a bit of practice, and you may have to delete the feature a couple of times
- Save your edits and close the Editor
The resulting rectangle should look similar to the image below:
- Open ArcToolBox –>Data Management tools –> Raster –> Raster Processing –> Clip
- Input DEM
- Output Extent is the clip_area layer
- Output is s clipped DEM in your lab8 folder (i.e quesnel_lake_dem_study.tif)
Now clip out the vector layers as well
- Arctoolbox –> Analysis tools –> Extract –> Clip
- One at a time clip
- the contours, roads and lakes (input layer)
- with the new extent layer your created (clip layer)
- and create three new clip layers (i.e lakes_study.shp)
We now have a nice set of layers to create a map with
2. Setting up your 2D version of the map
This section is essentially a repeat of the steps you took last lab whereby you styled layers in such a was as to produced a combined shaded and tinted surface. Last lab we created layer styling to take in to ArcScene. This included a satellite image.
I this part of the lab, you are re-create some style layers for use in ArcScene and an Open Source piece of software for 3D perspectives. You are not going to use a satellite image, and you will be using the Quesnel Lake dataset you just downloaded. If you do not remember the steps you took, you can refresh your memory using last week’s lab.
Preparing your map
Here are a few pointers to follow in combination with last week steps
- Start a new map and load in the study area versions of the DEM, lakes and contours layers into the map. You can use roads, but this scene has very few roads in its extent.
- Create a hillshade layer (as you did last week)
- Style the raster layers accordingly. This is where you can experiment, but the values Scott used this week for the DEM and the Hillshade are;
- DEM (no transparency, 10 contrast and -20 brightness)
- Hillshade (15% transparency, 10 contrast and -10 brightness)
- Save each of your raster layers as a lyr file
- right click the layer –> Save as Layer File (i.e. quesnel_dem.lyr)
- Style the contours with a fairly thin line (maybe 0.5 or 0.4 points) – you can always experiment later in producing your 3D view
- Perhaps reduce the number of contours. You can reduce the number of contours to show only those at 200 metre intervals by;
- Open the definition query tab in the layer properties panel
- place this code into the query pane - Mod(Round(“e”, 0) * 10, 1000)=0
- Style lakes with a suitable blue colour, BUT do not use an outline colour (or ensure the outline colour is the same as the fill colour)
- Save your contours and lakes as lyr files (as you did with the raster layers.
- save your map (i.e lab8.mxd)
Below is an example of the combined layer (click to see a larger view):
3. Using the layers and styling in ArcScene
Exporting the map for use in ArcScene
We are going to combine the two raster layers (DEM and Hillshade) into one raster layer, but leave the lakes and contours to be used on their own in ArcScene
- turn off the contours and the lakes layers
- export the map. File –> Export Map with the following parameters;
- export type TIF
- resolution 300
- write world file
- 24 bit colour
- write geotiff tags
- Save the file to your lab 8 folder (i.e. tints_hillshade_quesnel.tif)
Test ArcScene with the DEM and Hillshade layers
- Start ArcScene and load in the raster lyr files (just to see the problems we face).
- Try to see if you can make a nice looking scene with the styled DEM and Hillshade layers
- Do not spend much time here, just try the next part
Using the merged raster layers in ArcScene
You see that we suffer from the same issues as last week, whereby it is very difficult to get the shaded relief to lay over top of the DEM without the DEM layer poking through
- Remove the hillshade lyr file from ArcScene
- Turn off the visibility of the DEM layer
- Load the tinted hillshade tif file you exported into the scene
- Set up this layer in 3D mode (as you did last week) using the DEM as the base layer
- Load the contours and Lakes lyr files
You can play around with each layer in attempting to create a 3D perspective that has the lakes and contours rendered well over the surface of the DEM (i.e. you can try to offset the lakes and contours to have them present well in the scene). Do not spend much time trying to make this work, the next part provides a different solution.
Save your ArcScene project.
4. Open source software for 3D rendering
Using Terrain Bender
Exporting the map for use in Terrain Bender
We are going to combine the two raster layers (DEM and Hillshade) as well as the lakes and contours into one raster layer to be used in Terrain Bender.
- Export the DEM as another file type using ArcToolBox;
- ArcToolBox –> Conversion Tools –> From Raster -> Raster to ASCII
- Input (what do you think?…)
- Output a file in your lab8 directory with the extension (File Type) .ASC (i.e quesnel_lake_dem.asc)
- Export the map as you did for ArcScene (except set the resolution to be 500), but this time you will have the lakes and contours turned on as well.
- Once you have exported the file from ArcMap – Open it it the GIMP as follows
- Launch the GIMP;
- Start Menu on the Linux computer –> Graphics –> GIMP Image Editor
- Open the exported map from ArcMap (you should be in your home directory in Linux, so navigate to your geog205 folder to get to your labs)
- Clip out the map area of the export;
- Tools –> Selection –> Rectangle Selection
- draw out a rectangle around the map part of the image (to remove the white edges)
- Edit –> Copy
- Edt –> Paste and new image
- Save the new image;
- File –> Export as –> name it something like map_texture.png (use the png extension and GIMP will convert it accordingly)
- Slide the compression level to 0 (zero) –> click Export
Terrain Bender is an Open Source piece of software that renders elevation models into a 3D perspective. It also allows for an image overlay over a DEM. For more information, check out the web page for Terrain Bender
Go to your Linux desktop (minimize all the other programs -including osmotar). You can set up your scene in Terrain Bender by:
- Launch the program on your desktop labelled “Terrain Builder” (it used to be called that).
- At launch it asks for a ESRI ASCII Grid –> navigate to the ASCII (asc file) DEM file you created (i.e. quesnel_lake_dem.asc)
- This will load the DEM to the program
You can play around with the DEM by making use of all the different buttons and tools in the interface). If you screw up you scene, just reload the DEM again (File –> Open Terrain Model). Once you have become familiar with how the software works, load in the image you just clipped from GIMP;
- To load the image over (the software calls it a texture image)
- File –> Open Texture Image
- Navigate to the exported image you clipped in GIMP (clipped from the image created in ArcMap with the contours and lakes)
- presto magic
For the assignment below, you will need to be able to export your work in Terrain Bender. This can be done by File –> Export Rendering. This saves a png file that can be brought into Word for the assignment.
5. Open source software for 3D rendering
Assignment #3: Due Monday Mar. 20th
Repeat the process from the lab above for an area of your own – anywhere in Canada. Pick a area that is of interest to you. The general goal will be to enable your audience to visualize the area you choose and enhance their understanding. Your final product is the best view of the data.
Please make sure you can successfully download the data you need when your TA is around in case of any help you may need. You may also not want to make your stude area to large. The data used in this lab covered the area of 6 1:50000 NTS map sheets (you can see the sheets by turning on the button in the GeoGratis Extraction page). Anything larger may make ArcMap run slow.
Suggest to use WORD for write-up and insert all map images (PNG or JPEG files) exported from ArcMap and Terrain Bender into your WORD document
- Brief description of where it is and why you chose it (300 ~ 500 words, double spacing). Any issues (if any) raised with this dataset?
- A 2D map from ArcMap with major water body(rivers, lakes), roads (symbolize road based on attribute if possible), dem surface as foreground and hillshade underneath. Label 2~3 important features such as river, lake, highway or mountain peak etc. Note: the map should come with appropriate map title, legend, scale bar and your name/date etc. Export the map as JPEG file
- 3D image of the 3D visualization from Terrain Bender with major water body, roads ( if possible) , dem and hillshade. Choose a reasonable Vertical Exaggeration value. Select the best view location.
- List highest and lowest elevations on this map sheet. Check the elevation unit Contour Intervals and Elevation Unit
- Give the Vertical exaggeration chosen ( mountains may require a lower number, and the Prairies a higher number).
- Save your document as lastname_firstname_as3.doc or save as PDF file (this file should include everything: write-up, maps, 3d screen captures). Print out the file in color and hand it in to your TA or drop-off box 2O (staple them together)