Topography Map, May 2020

Topography Map Draped Over the 2-D Map

Precision 3-Dimensional Mapping

Aerial drones are the ideal method for collecting precision aerial mapping information for your land development projects. This is exciting technology and the map products that we deliver are truly breathtaking.

Each project begins with a client-provided map that outlines the site that needs to be surveyed. We enter this information into our drone’s autopilot (a mapping application), which flies the drone and collects the photos. Our typical settings are 90% overlap and 3 cm/pixel, which are further explained in our Orthomosaic Mapping and Photomapping blogs (parts 1 and 2).

We’re very good at photographing and delivering precision map products. As described below, several of these deliverables require specialized software to take full advantage of 3-D mapping. We do not offer professional cartography services, but instead provide these files to professionals who have the specialized software for these types of projects. The free software applications described below are suggested for viewing our products, but are not endorsed by FAD-Photo as suitable for professional-level mapping. We do believe, however, that many users will find them quite useful.

3-D Map Processing

Using our typical settings, the drone takes 18 photos per acre of land. For large sites, where we collect hundreds of photos, each pixel of the surface is examined at 13 or more different angles. Map processing aligns the pixels and assembles them into a 3-D composite model that includes latitude, longitude, and elevation.

Accuracy? Each photo is tagged with its position and altitude, so the composite model’s position is as accurate as the Global Positioning System. Typically, 3-4 meters.

Altitude information is based on the drone’s barometer, which has an accuracy of 3-4 meters. (We covered this specification in our April 23, 2020 blog.) Map deliverables are normalized to sea level.

Image processing is highly complex, so we use a professional mapping service provider. These are the deliverable products you will receive:

Full Color 2-Dimensional Map

This JPG file is a composite map of the photos, which are combined into a single panoramic map. Instead of a traditional scale, such as 10 meters per centimeter (or 100 feet per inch), the map service provides scale in terms of centimeters per pixel (or inches per pixel).

The JPG map doesn’t include position information, but its TIF counterpart (also a deliverable) has position information for each pixel. Use an application, such as the free QGIS software to view.

3-Dimensional Maps

DEM – Although monochrome, the Digital Elevation Model map (a TIF file) includes position and elevation information for each pixel. Special software, such as QGIS, must be used to view. The mapping service also provides a JPG of the DEM map, but this product doesn’t include position information.

Point Cloud – This is a LAS file, developed for LIDAR applications. At first glance, this full-color type of 3-D map appears fuzzy and not very useful. However, with a good viewer, such as the free Fugro Viewer, you can zoom in on the left panel image and view its corresponding 3-D model on the right panel. This is useful for looking at pixels under trees which would otherwise be masked. Of note, the 3-D model can be rotated in any direction with the mouse.

3-D Object Map – This is also a full-color map that can be rotated in any direction with the mouse. It offers a much sharper appearance than the point cloud, but it doesn’t get under the trees. Three files are required: the main 3D.OBJ file, a 3D.JPG file, and a 3D.MTL file. (You can rename the OBJ file, but don’t rename the other two.) You can open this type of map with the Windows 10 Object Viewer, but the free MeshLab viewer allows full 3-D rotation and zoom with the mouse.

Other Deliverable Map Products from FAD-Photo

The map processing report provides details on your map products, including map location, output size in pixels, scale in inches per pixel, overlap report, etc.

Topographical map (traditional contour map), where the user can specify the color scheme and contour intervals. (A postprocessing fee applies.)

Topographical map draped over the panoramic map. Here, the contour intervals are overlaid onto the full-color 2D map. An example is provided above and a larger example appears on our portfolio page. (A postprocessing fee applies.)

Do you have a special application?

Contact us for the solution. We’re experts in drone photography, mapping, and postprocessing services.



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