Tuesday, July 15, 2014

Photogrammetry versus LiDAR

Recently we have been conducting some further research on ways of effectively modelling, or extrapolating survey data from which to develop more accurate and detailed models of a build environment. Combined with this, we are also thinking of the possibilities for Landscape Architecture which could be further extended when coupled and integrating with similar fast approaches that have their origins in Matte Painting and Projection Models. In the past we have posted about, and on a number of occasions have used LiDAR ourselves, to gather a precise scan information sets of 3d data on a site, however we thought it was about time that we do some work with the ever more popular method of Photogrammetry. (that we actually post)

So what are the two and their differences?  
Well....     LiDAR is a remote sensing technology that measures distance by illuminating a target with a laser and analyzing the reflected light. (from wikipedia)
Where as Photogrammetry is the science of making measurements from photographs, especially for recovering the exact positions of surface points. Moreover, it may be used to recover the motion pathways of designated reference points located on any moving object, on its components and in the immediately adjacent environment. (from wikipedia)

It must be pointed out, that neither of these are new, and have been going through rapid development in the surveying disciplines in recent times. In fact, Photogrammetry was used before the Apollo missions to reconstruct and further understand, the surface of the moon prior to the luna landings (though mostly done by human calculations, rather than as it is today, with algorithmic software), and is still used widely being used today by NASA to model distant planets among other things.   Click Here to read more

Photogrammetry we believe, has massive potential due to it being a incredibly cheap alternative when compared to LiDAR. What was rather surprising when we first read it was that it can be as accurate, or indeed more accurate than LidAR if set up correctly with ground and camera positional data.

The others advantages (and there are many more) would be the cost affordability. This isn't just reflected in the software and hardware but the capabilities of light weight UAV Drones for their use in aerial surveying type applications instead of traditional aircraft.
Further advantages are the on site setup times, taking into account the actual scanning and processing are also heavily in favour of Photogrammetry over LiDAR.
So this is where we still felt we needed to test and document some of these capabilities for ourselves.

We will be detailing the tests that we have conducted soon in coming posts, and are just editing some quick films for each.

Two interesting articles we found comparing the two, if you are interested are:

Aerial Perspective: Photogrammetry Versus Lidar

Scanning the margins

Some Past Posts on this subject:
UAV mapping of antarctic
Modelling London