When doing a virtual survey, it is sometimes easier to look at the terrain through a different set of "glasses". Terrain Lenses are a set of visual tools built into Virtual Surveyor that enhance the ability to interpret, modify, and survey the terrain through displaying different visual filters over the terrain.
This article will explain the Terrain Lenses in Virtual Surveyor and lists some common uses for each one.
Terrain lenses are enabled & disabled through the Terrain Lenses section of the Analysis tab.
However, the Hill Shade lens is an exception as it is displayed passively when no orthophoto is enabled in the project. Terrain Lenses can be used at any time, but they are especially helpful when looking for variations in the terrain that may not be evident from the DSM and Ortho combined. These can include uses such as the Slope Steepness Lens for finding breaklines, or the Contour Lens for flow lines.
Hill Shade lens
The Hill Shade lens creates shadows on the terrain that make it much easier to visually interpret the elevation data. These shadows allow you to see relief or changes in the terrain from not only a 3D perspective, but also a 2D top-down perspective.
The Hill Shade is important in both everyday use of the software, but also in cases where no orthomosaic is available, or the orthomosaic is not clear. It is particularly useful in the usage of lidar data in Virtual Surveyor, as in many cases there is not an accompanying orthomosaic to the lidar data set.
Some typical uses are listed below.
The Contours lens helps to denote elevation throughout the terrain in a more precise way through using isolines. By displaying contours you can quickly recognize common elevations, quick changes in elevation, or areas of little to no elevation change. The Contours lens also contains a interval function that allows you to control the spacing of contours dynamically, with changes showing up immediately in the Viewport. Major and minor contours are also displayed, with every 5 intervals displaying a darker line for the major contour. You can choose the color of the contours in the settings next to the Contours button.
Some typical examples are listed below.
Slope Direction lens
Slope Direction is a unique tool to Virtual Surveyor that dynamically displays the direction of a slope through an easy to understand arrow graphic overlaid onto the terrain. The arrows will point in the direction of down slope based off the currently displayed terrain and area. The Slope Direction arrows will also dynamically adjust in size and frequency depending on the scale at which you are viewing the terrain. You can choose the color of the arrows in the settings next to the Slope Direction button.
Slope Direction is a great tool to understand the hydrology of a location. Some typical examples are listed below.
Slope Steepness lens (First palette)
The Slope Steepness lens is an alternative way to view elevation changes that focuses attention on areas of rapid elevation change. Areas of steeper slopes will be colored in more intense colors (red, orange, and yellow), while areas of lower or no slopes are colored in shades of blue and up to green.
Slope Steepness has many uses from safety (landslide) to making tools easier to use (digitization of top or bottom of features). Some typical examples are listed below.
Slope Steepness lens has 2 palettes to choose from. This view is the default palette for Slope Steepness.
Slope Steepness Threshold lens (Second palette)
The secondary view palette for Slope Steepness allows you to only view slopes over a defined percentage, or threshold. You can access this lens by clicking onto the Palette button next to the Slope Steepness button and selecting the second option.
When set to threshold mode, the Slope Steepness lens will visualize any slopes over the input threshold percent as red. The Slope Steepness Threshold lens is an important tool in locating slopes exceeding certain values.
This is a Mountain & Peak feature.
The Transparent lens allows you to see through the terrain and thus display any features that are beneath the terrain or going through it.
Oftentimes features digitized as points lines or polygons in one data set and point in time, can be underneath another data set at a different point in time. This can be the case due to changes in the terrain itself or vegetation growth obscuring the feature. Many types of work also focus on subterranean features such as mining, subsurface utility locating or engineering.
Typical uses are listed below.
The Elevation lens is used to represent elevation throughout the data set as a color gradient. The Elevation lens helps differentiate elevations, and can be very helpful on very large data sets. A specific elevation range can also be set by putting in either a Min and / or Max value. Typical uses are listed below.
Beyond individual lenses being displayed one at a time, you can also display any combination of lenses at the same time. Any combination of lenses can be enabled through turning individual lenses on and off. By doing so you are empowered to use these visual analysis tools in a way to makes discovering or extracting the data you need easy.
Lens Combinations open up the use of drone data in Virtual Surveyor to most application. Find what works best for you!