My goal is understand how the software compare the different point clouds when I have done a survey with two different techniques (for example, Laser scanner and Photogrammetry). I have tried with two different software and I have found two different results, so, how can know which is the correct or maybe more correct?
Has anybody written something about it? Thanks!
First of all you need to do coarse registration between both of the data set with respect to with respect to the laser scan coordinate system unless if the phtogrammetry point cloud georefrenced based on GPS/INS. The second step there is three different algorithm common, the first one is point to point comparison or call cloud to cloud. I don't recond this because the point cloud irregular but if you can make the point cloud regular grid I recommend you use this method without any problem. The second method is surface to surface comparison, basically this method the same of the previous one because it is compared based on pixel to pixel. My suggestion is to use point to surface comparison because this method more accurate especially when one of the scan has some occlusion.
Hi Abdulla!
Thank you for your answer. Yes, I know about these 3 different ways, but I would like to know more about it. Do you know if someone has written about this? Which are the algorithms? I found these ways in the Cloud Compare manual, but I want to know if someone han done some tests in order to understand which is better in different cases study and to do these 3 kind of comparisons which is really the process for each one?
Comparing Two Methods of Surface Change Detection on an
Evolving Thermokarst Using High-Temporal-Frequency
Terrestrial Laser Scanning, Selawik River, Alaska
Method of correlation is supposed to get understanding of the problem. In general, it gives good results as well. Detail can be found in books on digital photogrammetry.
Thanks Abdulla! I have found the answer in this article and in the bibliography of this. Your answer has been very helpful for me.
A open source software named CloudCompare provides some comparision methods. I think you can try it to see wheather to meet your demands.
You can find some information about 4 different algorithms in the Paper "Change detection in Terrestrial Laser Scanner Data Via Point Cloud Correspondence" from M. Tsakiri & V. Anagnostopoulos.
The algorithms they compared are Nearest Neighbour, Nearest Neighbour with local modelling, Normal Shooting and ICP.
Article Change Detection in Terrestrial Laser Scanner Data Via Point...
I usually use CloudCompare, an open source software that enables cloud to cloud or surface to cloud comparison. It is simple to use and gives good results. The first provides results in terms of absolute distances while the second in terms of signed distances. All of them gives the the probability distribution associated. you can choose from different algorithm to make comparison: nearest neighbor o least square and other...
David thank you so much, I just was searching these algorithms! I knew the software but I wanted to know how the software work. Thanks!
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