I wanted to correct this post because apparently, what I heard was not exactly what was said but it was inferred and some folks in our industry believe that TerrMatch is the only way to effectively calibrate. This post earlier today has had alot of action and I am glad it has started some good discussions about calibration because calibration is probably the most important function in LiDAR processing, but if you feel differently please feel free to comment. I always want to stir discussion but I also what to report events correctly so thank you Jim for commenting back on this.. See original post below:
My original post but not entirely true, it was inferred that TerraMatch is the only way to properly calibrate.
Although, I was not in attendance at the recent MAPPS meeting, LIDAR calibration was a topic of discussion. It is my understanding that it was indicated “that the only way to properly calibrate LiDAR was by using Terramatch”. I find this statement extremely incorrect.
I have experience calibrating using Optech, Leica, Reigl and several homegrown developed calibration processes including Terramatch. They all have yielded excellent results and in particular the manufacturers latest calibration software packages have showing exceptional results. Although, Terramatch can calibrate data well, I continue to be concerned with the assumptions it makes about the Sensors. I like to use Terrascan to fine tune the calibration and resolve very small errors if I use it at all. I guess the best way to sum up calibration is by something I used to say to one of my LiDAR technicians early in my career when he would beat on his monitor, “The computer is only as smart as the operator” and the same goes for calibration..! Comments welcome about your experience with calibration.
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Some of my issues with terramatch are
1) It’s primarily designed to work with Applanix IMU’s (at least thats what it said in the last verison of the manual). What about other’s?
2) You get different results each time you run it, even with the same data. I have no idea how much this impacts the final solution, but it doesn’t quite sit right with me.
Having said that, it runs side by side with Microstation and Terrascan which is handier than having to install and licence a new package like RiProcess or other proprietary software.
Considering how much people pay for MMS scanners and IMU’s, and how important calibration is to their use, im surprised that calibration software doesn’t come free with the hardware.
Extremely incorrect? I find that Terramatch is simply one of any number of software packages/method that can be used to calibrate LiDAR. The more tools/methods that are available to do a job the better, potentially the better the job can be done.
Jamie,
I was at the meeting and I also was one of the panel members. Whoever reported this to you is reporting incorrect information. I clearly stated that using third party solutions not associated with the manufacturers software will not deliver optimal results. I was very clear.
The most effective way to correct for the angular mis-alignment between sensors – the so called “boresight” calibration is in the manufacturers software. Riegl includes this in its processing package. The reason why it is most effective is that it uses planar surface matching to find tens of thousands of planes(rooftops) in the data from overlapping flight lines. The corrections have access to the sensor calibration in the Riegl Software which is the most accurate way to reduce the mis-alignment. The methodology is rigorous and reliable. Riegl incoporated this in 2003 and in subsquent years other manufacturers began to follow this approach.
The Terramatch was a historic answer to the lack of this methodology from the manufacturers. At the time it was as good as it got. This methods haved been adopted by other softwares without a clear understanding of the manufacturers progress.
I hope this helps.
Best regards,
Jim Van Rens
Jim,
Thanks for the feedback and I tried to correct the post because of your comment. I am happy that alot of folks are commenting on this, as it is a very important topic and the manufacturers of LiDAR Sensors don’t always get the due credit for the extensive work they do to provide users with better tools.
Jamie