Amusing Monday: Amazing images through the magic of LIDAR

Spectacular images produced with the latest LIDAR technology ought to be considered works of art, at least in my humble opinion.

LIDAR software reveals current and historical stream channels for the Sauk River, a tributary of the Skagit.
Image: Washington State Geological Survey

The images on this page, which show geologic features in Washington state, were produced as part of a large-scale project to study the state’s geology. Funded by the Legislature in 2015, the project is largely designed to identify landslide hazards, but the LIDAR data has many wide-ranging uses for scientists, educators and political leaders.

Aside from LIDAR’s practical uses, I cannot get over how beautiful the images are, a feeling enhanced by the knowledge that the fine details reflect actual structures on the ground. All these images and 14 others are available as screensavers on the state’s LIDAR website.

At the Great Bend in Hood Canal, moving glaciers once carved out small hills, known as drumlins.
Image: Washington State Geological Survey

I asked Dan Coe, a GIS cartographer responsible for many of the final images, how much of an artist’s touch he uses when producing such amazing depictions of the landscape. Dan works for the Washington Geological Survey, a division of the Department of Natural Resources.

“There is definitely an artistic touch that is added to these images when they are produced,” he wrote in an email. “While each one is a bit different, depending on the landform featured, most follow a general process.”

LIDAR reveals changing stream channels where the Black and Chehalis rivers merge in Grays Harbor County. // Image: Washington State Geological Survey

LIDAR stands for light detection and ranging. When used from an airplane, LIDAR equipment shoots a laser beam along the ground. Sophisticated equipment and a computer interpret the reflected light as precise differences in elevation.

Dan blends the elevation data with other GIS layers provided by the software, including the outlines of landforms, shaded relief and water bodies.

“I then bring these layers into graphics software (usually Adobe Photoshop or Illustrator), where they are merged together,” Dan said. “This allows me to emphasize the features that are important to the viewer, usually with colorization and blending techniques.”

LIDAR reveals details of Devil’s Slide on Lummi Island in Whatcom County that cannot be seen otherwise.
Image: Washington State Geological Survey

The primary purpose of the images is to translate the science for a nontechnical audience, he said. That’s not to say that scientists don’t appreciate the effort, but the colorful images are somewhat simplified from the more detailed LIDAR data, he added.

“If done well, they are a good example of the ‘a picture is worth a thousand words’ adage,” he said, “and can go a long way to bridging the gap between science and public understanding.”

When it comes to his choice of colors, he acknowledges that he strives for a bit of a “wow!” factor, while enhancing the contrast “to draw the viewers eye and to emphasize the features more clearly.”

The video at right offers a good description of how LIDAR works. Early uses involved examining the topography and geology of an area with the trees stripped away. The surprising images revealed unknown features on the ground — including a piece of the Seattle fault at the south end of Bainbridge Island, where an earthquake raised Restoration Point about 20 feet some 1,100 years ago.

Since then, LIDAR has been refined for greater image resolution, and the improved software is providing new ways to interpret the data. For example, relative elevation models, or REMs, help to better visualize changes in river flows over time. The baseline elevation (0 feet) is defined as the surface of the river, so old river channels emerge as slight changes in elevation. Dan explains the REM process (PDF 16.5 mb) in a poster on the LIDAR website.

The mysterious Mima Mounds southwest of Olympia, as shown with LIDAR
Image: Washington State Geological Survey

The early use of LIDAR for revealing unseen geology has gradually given way to much broader applications. At first, the returning light that reflected off trees and vegetation was considered useless “noise” to be filtered out by computer. Later, scientists discovered that valuable information could be found within that noise — such as the size and type of trees and other vegetation growing in specific areas. These uses are explained in a video called “Introduction to Light Detection and Ranging.” Both videos mentioned in this blog post were produced by the National Ecological Observatory Network, or NEON, which is researching conditions and changes in ecosystems across the country.

A little-known lava flow, called West Crater, can be seen easily with LIDAR. The site is between Mount St. Helens and Mount Hood in Gifford Pinchot National Forest in Skamania County.
Image:Washington State Geological Survey

As Coe and his colleagues find new uses for LIDAR, they are also looking for new ways to encourage the public to understand the process and results. A nice two-page summary about the LIDAR program (PDF 2.6) can be found on the state’s LIDAR website. The website also includes descriptions of how LIDAR can be used in geology, forestry, graphics, navigation, meteorology and fire management, land-use planning, archeology and agriculture.

The page also includes an interactive story map called “The Bare Earth,” which takes you through various geological features. Interesting comparisons between LIDAR images and aerial photos of the same areas are shown in the story map.

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