The short of this is – Post-processing our True View 3D Imaging System (3DIS – laser scanner fused with camera imagery) data to a colorized point cloud is hours faster than processing photogrammetric images to a colorized point cloud. This savings in time can have a big impact on project Return On Investment (ROI)!
We have worked with a quite a few customers who perform routine volumetric surveys on a variety of materials. Most of these are in the mining sector, but there are certainly many other application areas such as road work cut & fill operations, stockpile yards and so forth. One quite interesting operation is managing feeder stock inventories.
We have been working with Packaging Corporation of America (PCA) for the past 5 years on feeder stock inventory measurement techniques. For PCA, the feeder stock is raw pulpwood logs that are ground into chips to feed the pulp process. PCA needs to perform a number of volumetric inventories on a monthly basis of various materials (raw logs, chips, etc.) in this process. Some years ago they migrated from using a contracted service with a manned aerial photogrammetry company to internalizing drone mapping using photogrammetry (GeoCue’s Loki direct geopositioning system on an Inspire 2 drone).
We have recently been experimenting with our True View 410 3DIS to see if we get better definition of logs in the colorized LIDAR than we do from an image-derived point cloud (e.g. photogrammetry). An example of an area of a log yard is shown in Figure 1. The data in this figure are the colorized 3D point cloud produced in True View 3DIS prost-processing. As expected, the detail is much sharper with the colorized LIDAR from the True View 410 though in clear areas this will not have a statistically significant impact on the computed volumes; photogrammetry is good enough if you don’t have to deal with overhead structures.
However, the big deal in this type project is time. The flight time for photogrammetry is just about the same as it is for the True View 410 3DIS (14 minutes for the example of Figure 1), so let’s focus on comparing post-processing. The complete workflow from plugging the True View 410’s memory stick into the PC resulting into a fully colorized, high accuracy point cloud is a bit less than 10 minutes. The time for processing drone imagery through Agisoft Metashape (the fastest of the structure from motion photogrammetry systems) is 3 hours and this is only if you have direct geopositioning; it is half an hour longer if you have to measure control! The volumetric analysis time for both is the same (using our True View Evo/LP360 tools) so, again we leave this out of the comparison. This is pretty amazing! If you ignore transit time (e.g. did the processing on site with a laptop), you could process raw data to final volumetric output in 30 minutes for this log yard site. The process for the same site using photogrammetry approaches 4 hours.
When we built the True View 410, we knew the data processing workflow would be quite a bit faster. However, since the photogrammetry time is batch processing, we did not think this would be much of a factor. However, when we start stacking projects together and trying to get through data sets, the difference is vast! The throughout ROI on the True View 3DIS systems is just night versus day as compared to photogrammetry.
If time is money, the True View 410 is a money generator as compared to a photogrammetry only approach!