How to create a Digital Elevation Model from Photosynth point clouds

How to create a Digital Elevation Model from Photosynth point clouds

Recent developments in the Open Source community have made it easier to create 3D models from point cloud data derived from Structure from Motion (SfM) technologies such as Photosynth and Bundler. This article outlines the steps I use to create Digital Elevation Models (DEM) from data acquired from kite, blimp, and UAV aerial photography.

In order to standardize this tutorial, I’ve created a set of data that you can follow along with using a Windows based computer. All of the concepts described here should also work in a Linux environment with little modification. Useable examples of all the files created during this tutorial are available for download at www.palentier.com/DEM_Tutorial .

The point cloud used in this tutorial was created by me and is located on the Photosynth website at http://www.photosynth.net/view.aspx?cid=14d8887c-7475-42d5-b810-c6642eace2c5 . The photographs that make up the synth were acquired from Kite Aerial Photography (KAP) and are of archaeological excavations at a pre-Inka tola site near the village of Palmitopamba in Ecuador.

I have attempted to use as many free and open source applications as possible but the final steps are completed in the commercial ArcGIS software. ArcGIS is the most widely used GIS program in the world and most users will probably be familiar with it.

The software needed for this tutorial are:

• Photosynth (which requires Silverlight)
• Photosynth Exporter
• Meshlab
• Excel or Open Office
• Notepad (built into Windows)
• ScanView
• Java Graticule 3D (JAG3D)
• ArcGIS with Spatial or 3D Analyst