Striking LiDAR Map Reveals “Hidden” Features of the Baker River

Steve Boynton is a long time Surfer user and beta tester who runs his own consulting company: Subsurface Environmental Solutions LLC. Recently, while catching up with Steve he shared an eye-catching LiDAR map that strikes a fine line between science and art.

Steve was inspired to create this style of map after coming across the “LiDAR Art” featured on joemaps.com. Being the son of an engineer and artist Steve has felt for some time that there is a lack of truly striking graphics being used in the Environmental Services industry. After all a compelling map really can say a thousand words.

As the owner of a heavily wooded property in the White Mountain National Forest of New Hampshire, Steve has spent extensive time exploring the hidden topographic and drainage features of the area through the lens of LiDAR. Due to this familiarity, he quickly thought of a prime river channel to begin experimenting with the technique, the Baker River.

Why is the Baker River Interesting?

The Baker River is only 35 miles long and starts at one of the highest peaks (Mt Moosilauke) in The White Mountain National Forest. It eventually flows into a 5-mile section of low broad valley near the village of Rumney. The stretch is notorious for its dramatic “oxbowing”. An oxbow lake is a U-shaped lake that forms when a wide meander of a river is cut off, creating a free-standing body of water. If this Lidar technique could be applied to the oxbowed stretch of the river valley it would really highlight these unique hydrologic features that can be missed when viewing a simple aerial image.

Aerial image of the Baker River displaying several oxbows

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Aerial Image of an oxbowed section of the Baker River near Rumney, NH.

Colormap Editor dialog in Golden Software's Surfer

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Colormap Editor when setting the two-color color scheme, 542.8 is the maximum elevation value being ignored.

Transforming LiDAR Data into a Striking Map

In order to create this artistic map-style you start by generating a Color Relief map from your Lidar data. In this case multiple Lidar “tiles” are imported into Surfer. To find the Lidar data tiles used to create the map of the Baker River, Steve used open-source data from the New Hampshire’s Statewide GIS Clearinghouse website.

After the Color Relief layer is created you choose a maximum elevation value that you hope to ignore. This will help reduce the noise of features that you don’t necessarily want to focus on. Once the maximum elevation value is decided you can apply a custom defined two-color, color scale where the background color is set to anything above your max elevation value. Choosing a color scheme is the greatest challenge, as there are infinite possibilities, and the best look is subjective.

Once satisfied with your color scheme you can further highlight the more linear, subtle features by applying a small vertical scale factor. Increasing the Z value scale factor can help sharpen the image quality, but it also can introduce more of the “noise” we are aiming to reduce. Overall, it really takes some testing to find the right balance between the Z value scale factor and color scheme as it pertains to your own data, so hop into Surfer and try it out!

Revealing the Baker River’s Hidden Hydrologic Features

After the workflow is applied to the Baker River patch of Lidar tiles you can see just how striking the river channel and the oxbow lakes (whether currently filled, or drained by historic environmental factors) are against the dark background. For artistic purposes it is sometimes desirable to perform post-processing in Photoshop for minor touch-ups, color-correction and sharpness.

Lidar map of the Baker River after a Z-scale Factor and Color scheme are applied in Surfer
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LiDAR Map created in Surfer compared to aerial image of the Baker River

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LiDAR map and aerial image overlay demonstrating the river channel and oxbows

To further illustrate just how well this map style highlights the channel and oxbows, enlarge the image to the left overlaying the original aerial image to the finished LiDAR map. You can see exactly where the colorized river channel merges with the aerial imagery and well the two images line up.

Analyzing Surface Water Level with Surfer’s Profile Tool

While revealing these subtle features is impressive enough, we can learn even more about the river valley by using Surfer’s features such as the Profile tool. By dragging the Profile tool’s guideline through the river channel and its corresponding oxbows we can create an elevation profile demonstrating the surface water level of the river at these points of interest.

Dips in the elevation value represent areas the guideline crosses the river channel or an oxbow lake and the surface water level at that point (See red arrows).

Surface water level profile map of the Baker River created with Surfer
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Golden Software loves to highlight how our users are creating maps and gaining a unique perspective of what can be done within Surfer. We would like to thank Steve Boynton for working with us on this blog. You can follow the links below to learn more about his work and the data used for this article.

Steve Boynton Instagram: @subsurface_env

Data References:

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