- 1. Introduction
- 2. Contour Lines
- Creating a DEM
- 3. Hill-shade
- 4. Creating 3D Scenes (This is where the computer will slow down)
- 3D Navigation
- Hypsometric tints
- 5. Fly through
- 6. Assignment 5 (5%) due before next weeks lab
1. Introduction
This year is our first second year with new computers so we hope for a smooth lab (last year actually went quite well). With that said it is important to keep in mind that 3D is inherently more computationally intensive; and when working inside of ‘scenes,’ operations will take longer to complete, and the software may be more unstable than normal. We have lots of time in lab today, save often, and if something doesn’t work quite right, stay calm and remember we are here to learn.
“To lose patience is to lose the battle.” – Mahatma Gandhi
This is simply the reality of working with large files in real-time 3D (a note from Matt: I have done this type of work once where all the motions and animations in the previews felt smooth; and that was on a $20,000 computer to provide some context).
When working on your homework you have an extra incentive this week to complete in lab as opposed to using Osmotar as the 3D performance is substantially higher on the local computers as opposed to remote desktop.
2. Contour Lines
In lab 4 we used contour lines on our map of Smithers, and today we will be taking it a step further and instead of just placing these lines on the map, as is common on topographic maps, we will be using the contour lines to make a digital elevation model, and add some shadow effects.
Open your colour map of Smithers from Lab 4 (if you for some reason no longer have your lab 4, you can copy this directory L:\GEOG205\lab06\smithers into your K drive and open this project in ArcGIS Pro).
Creating a DEM
Open the Tools pane from the Analysis tab
Search for the “Topo to Raster” tool
Set:
Feature Layer to contour
Field to ELEVATION
Type to Contour
Output cell size to 30
For output extent choose contour from the drop down (Note the text will revert to As Specified below, but the numbers below will have updated).
Leave all other settings on default and press run (This will take 1-2 minutes to complete)
Next in your drawing order turn off contour and vegetation.
Select the new DEM layer you created, and set the symbology to stretch
You should have something as below
As you can see in this digital elevation model the pixels of the image represent the elevation, white pixels are the highest values and therefor the highest elevation.
It is likely more common to receive elevation as a DEM than as contours. Note that if you want to make a topographical map, you could produce the contours from the DEM with the “Contour” tool. We will not be doing this in today’s lab, but the process is very similar as above: simply pick the input DEM, give it an output name, and set the interval. (This is also the best way to convert contours from Feet to Metres while still having even number, though note this will reduce data quality due to interpolation)
Discussion Question: What was the contour interval for the Smithers data-set?
3. Hill-shade
Digital elevation models are not the most visually appealing on their own, so to add some visual style we will create a hill-shade.
Create hillshade
Select your DEM (if you never altered the output it will be called TopoToR_cont1)
Open Raster Functions
At the very bottom you will find Surface > Hillshade
We will start by making a Traditional Hillshade:
Select your DEM created in previous step from the drop down, and leave type as traditional.
Azimuth is the compass direction the ‘sun’ will be coming from to cast shadows. 315 degrees represents North West. If you want your shadows on the other side of the mountain this can be changed.
Altitude is how high on the horizon the ‘sun’ is in degrees with 0 being at the horizon (very strong shadows cast), and 90 being directly above (very few shadows, with no discernible direction).
This should produce results as below
If you want to avoid shadows all being on one side of the terrain, instead of setting the Altitude to 90 degrees, use multidirectional as opposed to traditional hillshade.
Finally
Turn off the DEM, and all but one of the hillshade layers you just made
Ensure World Topographic Map, and World Hillshade are turned off.
Move the hillshade layer you still have turned on to the very top of the Drawing Order.
In the top ribbon, under Raster Layer, set Transparency: 60%, and Layer Blend: Luminosity
Your map should now have a nice 2.5D effect
4. Creating 3D Scenes (This is where the computer will slow down)
Open ArcGIS Pro Again and Create a new Local Scene from the templates and name your project lab06-3d
Now let’s examine the drawing order for the Scene. In the map we had only a single category and now we have three categories.
3D Layers: this is for layers that have elevation information attached (i.e. contours). We will not be using any of these right now, these layers will be displayed at an altitude based on the contained data.
2D Layers: these are the layers you have been working with to date, and function exactly the same as they did in the map, except they will be draped over an Elevation Surface
Elevation Surfaces: this is the 3D data that 2D layers will be displayed against.
*Note on 3D Layers, the elevation can either be above ground level or absolute. When elevation is absolute, errors in alignment between 3D Layers and the Elevation Surface could cause the layers to end up below the ground and thus not visible.
We will start by turning off all 3 of the default layers, giving us a clean canvas to work with.
Add a folder connection for the Lab 6 data L:\GEOG205\lab06
Right Click on Ground in the drawing order and Select Add Elevation Source, in the lab06 folder you will find an alps sub-folder and a layer alps_dem.tif select this layer. Note you will not yet see a change take place.
Next add the apls_ortho.tif file just as you would to any other map from the catalog.
3D Navigation
You can use the 3D interface, which can be a little un-intuitive at first. You can also use the mouse movements below to control the map. Spend a couple of minutes exploring the alps and getting a feel for how to move the map around all of its axes.
Pan map – Left Click and drag
Zoom Map – Scroll Wheel or Right Click and Drag
3D Tilt – Middle Click and drag or [Shift] + Right Click and drag
Hypsometric tints
Note that the process for creating hypsometric tints is identical on the regular 2D Maps.
Start by adding alps_dem.tif as a visible layer
Next go into Imagery then Raster Functions
Search for “Shaded Relief”
Set the Raster as alps_dem.tif, and pick a suitable Color Ramp: Note that Left to Right is low elevation to high elevation.
Do this process a couple more times with different colour ramps to see how the appearance changes. Note that different terrains will look better with different color ramps.
As a general note, ramps starting with a blue are generally only appropriate when the scene contains water, in which case it should be adjusted so the blue represents the waterline. As an example of this take a look at the default colour ramp below, aside from the red being overpowering, notice how if you did not know there was a settlement in the valley this image makes it appear as though there is a river, and the tan looks like a beach-line. This is not helpful for your end users!
Note if your terrain looks too flat (or not flat enough) you can change the vertical exaggeration. Select Ground in the drawing order.
Then go into the Elevation Surface Layer tab and you will be able to set the Vertical Exaggeration.
When you change the exaggeration it will change the height of your map, and may take it out of your current view point, the easiest way to find your map again is to right click on one of the layers you added and zoom to layer.
5. Fly through
At this point we have a 3D scene that we can look around, set to the perfect angle and send someone else a photo of, however in some cases, it may be more beneficial to send someone a video of this scene. We will accomplish this through a process known as keyframe animation.
Go to View and Add Animation
A new toolbar will have appeared below your scene with only a single button. First, adjust the view to how you would like your movie to start, then press “Create First Keyframe” and your Animation Timeline will appear!
Next move your view to a different angle you would like to show off then press the Green +, and you will notice a 2nd frame.
If you press the Play button you will see the scene calculates all of the in-between frames to make an animation (though it will still be very choppy at this point!).
You can continue adding as many frames as you like to create a tour of the scene.
When the animation works the way you want it to, it can be exported as a movie, this goes through a process called rendering. We will not be exporting the movie as part of lab as this process takes several minutes to an hour depending on the length of your animation. The time this process takes to complete is the reason why the preview was choppy, the computer is unable to process frames of the movie as fast as it would need to in order to create smooth motion. However the exported movies would play back smoothly and could be shared with clients or on social media.
6. Assignment 5 (5%) due before next weeks lab
For this weeks assignment we will be building a simple map of Prince George, all of the layers you need are in L:\GEOG205\lab06\Assignment. You will be submitting two maps again this week.
Part 1
1.) Make a simple map, using the Road Centerline, Trails, Building Outlines, and Hydrology, (you will also use Contours to build a DEM)
2.) Convert the Contour Layer into a DEM – Use 20m cell size (This will take about 4 minutes to process, a good time to stretch, or grab a coffee!)
3.) Create Hillshade From the DEM
4.) Use the hillshade to add the visual relief (Note: do not use the “shaded relief tool” just the hillshade layer) as we did on the Smithers map at the beginning of lab.
5.) Create a Map Layout of this and export it as a PDF to submit.
Part 2
1.) Add a new local scene to your project Insert > New Map > New Local Scene
2) Replace the elevation surface with the DEM you created for the first map. (You will find it inside of your projects default database in the catalog.)
3) Add the layers for Roads, Trails, and Building footprints.
4) Find an interesting viewpoint for your 3D map, note that you will most likely need to increase the vertical exaggeration as Prince George is relatively flat. Also, consider changing the basemap to get a more pleasing appearance.
5) Create a new layout. Scenes can be added to layouts through the same process that you added the map frame in part one of the assignment (and every other assignment so far).
6) Add your name and title, for the 3D scene the legend is optional. Scale Bars and North Arrows should NOT be used as they will be incorrect due to perspective.
7) Again, export your map as a PDF.
Submit both maps to your TA through Moodle.