More 3D Maps and Tips Using QGIS2threejs

After last week's popular post, here are few more maps and tips using the QGIS2threejs plugin.

The Maps

1. 3D Chloropleth Map of Crime Counts by Police Beats in Chicago, 2013
2. Visualization of Mt. Rainier, Seattle
3. Groundwater Depths in Three Counties in Nevada

Data sources and references:
Open Data Chicago
Chicago: Official Police Maps (CLEARMAP)
National Map Viewer
Nevada Bureau of Mines and Geology

When viewing the maps, if a black box appears instead of a basemap, try refreshing/reloading your browser and the basemap should display properly.

The Tips

3D Chloropleth Map:  Here is a trick to create a 3D chloropleth map on a flat surface.  The plugin won't run without a digital elevation model (or DEM) raster, but you can 'trick' it into using a flat raster.

• Updated(12/9/2015): The plugin now allows users to select a flat surface/no DEM used
• Take the raster calculator and exponentiate/raise all cell values to the power of 0 (rastervariable^0). The resulting raster will be flat with a value of 1.  Alternatively, multiply by zero.  (You may also have to symbolize null values as well.)
• Classify and symbolize the polygons using your desired color scheme--before using the plugin
• In addition, I changed the color of the raster file in QGIS to match the background in the *.html file (#ccccff). 
• I added HTML code for a basic legend using frames (90% for the map, 10% for the legend)

Basic HTML code sourcing the two frames.  The "Chicago" frame was generated from QGIS.
The "Legend" frame was a simple piece of code directed to a JPG of the Legend.

Screenshot of the final map and legend.

Mt Rainier:  Instead of using a web service, I download imagery and used the Build Virtual Raster in QGIS.   I used a detailed DEM and imagery from the USGS's National Map Viewer.  You can download files from USGS by using a bounding box, for example.  I used a vertical exaggeration of 1.1 in the plugin.  Click the screenshot below to enlarge a comparison of between Google Earth and the plugin's version of Mt. Rainier.

Left: Google Earth, Right: Plugin result using files from USGS

3D Groundwater Depths / Underground:  Using point data with depths, you can either select a negative multiplier in the plugin or create a new variable and multiply your depths by -1.

If your depths are positive values, select a negative multiplier in the plugin.

An overhead and underground view of the map.
The orange boundary represents three counties of interest.

A Free Look at the Luxor Hotel in Las Vegas

A while back, I wrote a brief post on FUSION LIDAR viewing software.  In this post, I will use real world data with the FugroViewer, freeware from the Dutch company Fugro.  

I downloaded LIDAR data from EarthExplorer -- focusing on downtown Las Vegas, specifically the pyramidal Luxor Hotel. The hotel's shape is so constraining that it needs specialized elevators, which tilt and shimmy, up to visitors' rooms. Of course, it is noteworthy to mention that LIDAR is also being utilized to search for ancient lost pyramids.

At first glance, the Luxor hotel is hard to pick out.  However, increasing the point display size from the menu helps to highlight its unique shape. Alternatively, I could also have tried turning off some returns or chosen to highlight specific values for different LIDAR attributes. Redder points have higher elevation values.  Click on the screenshots below to magnify them. 

Can you see the Luxor Hotel?

LIDAR points can be converted into TINs to help visualize what we are looking for.  The three panes below show three different views: overhead (left), a cross-section profile (upper right), and 3-D (bottom right).

Left: Overhead view with a view selected with the Profile tool.  Top Right: View from the Profile Tool.  Bottom Right: A 3-D view of the TIN generated from the LIDAR data clearly showing the Luxor Hotel and nearby attractions.

A slightly cleaned up 3-D view of the Luxor Hotel.

Lastly, LIDAR can be used to measure dimensions with great precision and accuracy.  The Luxor Hotel is listed at 107m.  Using the measurement tool, a height of ~ 107m  (104.7m) is calculated.

How tall is the Luxor Hotel?  Here, a quick measurement calculates about 105 meters-close to its actual 107m.

UPDATE on 1/25: I was able to add in imagery in Fugro viewer.  It has to be a single-band georeferenced image.

NEW: LIDAR data with satellite imagery underneath.

Google Street View of the Luxor and surrounding area

See also:
FUSION Viewer
LIDAR Exercises