Photogrammetry on the cheap

When I started looking at photogrammetry as a project for the Makerspace, my first impressions were of how expensive it was going to be. Expensive commercial software, expensive high powered computer to run the software on, expensive SLR camera to take the pictures, tripod, lights, filters, turntable…… the list went on and on.

I wondered if I could get usable results with what I already had, and the answer was yes. And there are three ways to go about it.

The pictures can be taken with a mobile phone, or digital camera, if you have one. Some sites suggest that the most important part of photogrammetry is the skill and technique of the photographer not how fancy the camera is.

The type of photogrammetry I am talking about involves walking around an object and taking multiple pictures from every angle. If the object is outside on a dull overcast day, no additional lighting will be required.

(1)  It is possible to manage without a computer.  Just use a mobile phone to take the pictures, then upload the pictures to the cloud based Autodesk Recap for processing. You need to set up an Autodesk account using an email address. There is no cost for this service. But Autodesk intend to start charging in December 2017.

Here are the results of my first test using a basic camera and autodesk Recap: https://blackpoolmakerspace.wordpress.com/2017/10/16/cloud-based-photogrammetry-tests/

(2) Some phones are capable of processing the pictures locally on the phone and do not even need the cloud. This Android app still supports the Samsung galaxy S3.  If you already have a supported phone, this is “one stop shop”  photogrammetry:-

https://3dscanexpert.com/3-free-3d-scanning-apps/ “This Android-only app developed by SmartMobileVision doesn’t feature any social features yet, or even an account registration system. But after logging in with a temporary username, it does have features that make it different than the apps above. The most important one is that it doesn’t do cloud computing but instead does all calculations locally on your phone. While the speed of this greatly depends on your phone’s processor—and naturally drains the battery”.  Tested camera list:-

Nexus 4
• Nexus 5
• Nexus 9
• Nexus 10
• HTC Desire X
• HTC One
• Samsung Galaxy S5
• Samsung Galaxy S III
• Sony Xperia L
• Sony Xperia SP

Results from a Samsung galaxy s3.

I rushed these pictures, in an effort to see the results quickly. I took 40 pictures of the same object and same light conditions as the Autodesk Recap test. Unfortunately, storm ‘Brian’ blew the ribbon all over the place, which messed up the front of the object (no movement is acceptable). But look at the back, it is spot on. The best part? Processing on the phone took 40 minutes. It took 2 hours on my computer.

 

 

Untitled Untitled1 Untitled2 Untitled3 Untitled4

(3) The third and last method is to  process the pictures with some free software called MVE :

https://github.com/simonfuhrmann/mve/wiki

https://github.com/simonfuhrmann/mve/wiki/MVE-Users-Guide

which will run on most recent computers. My computer is about 4 years old, it is an i5 with 8G ram and on board intel graphics. It took 2 hours to process 50 pictures. Nowhere near as fast as the computers normally suggested for the task, but my computer did the job and produced usable results. I have not tried to find out what the lowest specification MVE will run on.

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