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High-Resolution, High-Accuracy Topographic Mapping Services

Jon Coursey

The Harris Geospatial Marketplace offers a top-of-the-line photogrammetric mapping service called “HiDEM”. This service involves collecting a pair of stereo images to create high resolution, high-accuracy Digital Elevation Models (DEMs).  A team of experts with more than 25 years of photogrammetric mapping experience work behind the scenes on HiDEM to deliver the best surface and terrain models in the industry.

Figure 1 Overhead View of HiDEM Data

Project Deliverables

  • Key Deliverables:
      • 1 meter Digital Surface Model (DSM) data
      • 5 meter Digital Terrain Model (DTM) data
      • 1 or 2 meter Contour data (1m contours displayed in above image)
      • 0.5 meter Natural Color Ortho Image data
      • Highly accurate at sub-meter RMSE vertical using client-supplied ground survey control points (GCPs
      • Source Imagery: Pleiades-1, WorldView-2, WorldView-3 WorldView-1, & GeoEye

Why Use HiDEM?

HiDEM custom tasking is the perfect service if you need high resolution and highly accurate elevation data for a project site. Below are a few examples of how customers are using this data:

  • Drainage and hydraulic projects, such as mapping out sites to build a dam
  • Mapping out sites before building a mine
  • Mapping the area along pipelines for oil and gas industry

How It’s Done

Because end users will often have trouble sending a land survey to his or her project area (due to large area size, difficulty accessing the area, etc.), remote sensing is used. In this case, stereoscopic satellite pairs are collected. With our HiDEM service,  the points of objects on the ground are determined by our photogrammetric team from the pair of images. Lines of sight are constructed by finding the same points between the images, then determining the three dimensional location of each through the intersections of these lines. While the creation of the elevation model through satellite mapping is similar across the imagery, there are processes and algorithms used by our production team that make Harris Geospatial process unique.

The Harris Geospatial Marketplace Advantage

While many companies create elevation models with comparable resolutions, our hands-on approach delivers a more refined, better –quality end product. Our photogrammetrists take the time to look over each model of a project area to account for details that may have been missed. For example, with a 5 meter resolution terrain model, a pipeline in a project area that is say 4 meters in width would not show up in the raster image. A member of our team would identify this detail and add break lines around the pipeline to account for it. Many of our competitors generate terrain models automatically which would miss key details like this one and create the potential for costly problems down the road.

Additionally, our team will work with you throughout the project to make sure nothing is overlooked at any point along the way. A project manager will assist you in selection of ground control points (GCPs), defining area boundaries, and identifying other details that need to be addressed. As a distributor for all the leading satellite imagery providers with access to a large constellation of sensors, we can facilitate getting your job done quickly and efficiently, both in terms of time and money. Furthermore, with a large archive catalog to choose from, we can find the best stereo pair imagery and deliver it to you faster than a company who only works with their own satellites. All of these factors mean that Geospatial Marketplace customers get the best elevation models within the shortest time frame for the best value – hands down. Not a customer yet? Talk to us to see how the HiDEM service can work for you.