True View EVO, based on our widely-used GeoCue LP360 software, is bundled with every True View 3D Imaging Sensor (3DIS), including our subscription programs. True View EVO contains all of the workflow tools (including embedded Applanix POSPac drivers) for taking True View 3DIS data from the USB data stick containing raw observation data to a gorgeous, geocoded 3D colorized point cloud. But this is just the beginning for many projects.
While the colorized point cloud is a fantastic visualization tool, most projects aim to produce derived products. No worries – True View EVO contains a plethora of tools for creating a wide variety of products from point cloud data. In a previous issue, we took a detailed look at the volumetric analysis tools in True View EVO/LP360. In this issue, I want to take a step back and discuss why you would use a LIDAR system rather than photogrammetry for this type work.
Volumetric analysis within a point cloud setting is the process of using the point cloud to compute the volume of material. True View EVO contains an advanced set of volumetric analysis tools that allow for a variety of computational scenarios such as:
As an reminder, let’s take a look at a simple situation where we want to measure the volume of a stockpile that has an overhanging conveyor.
This scene, collected with a True View 410 3D Imaging System (3DIS®), is depicted in Figure 1. Note the useful display modes in True View EVO that make the situation with the stockpile easy to visualize. I have set the display to render by Triangulated Irregular Network (TIN) and shade by elevation color bands. Notice how we can very clearly see the stockpile as well as the overhead conveyor.
The process of computing the volume of this pile will follow a few simple steps:
True View EVO has a robust set of tools for manually and automatically digitizing stockpile toes. In fact, the automatic stockpile toe creation tool includes an option to detect and classify non-stockpile overhead features.
If the overhead structure is separated from the stockpile, the classification is “clean” and you will not have to do any additional work. If the overhead structure touches the pile (e.g. a conveyor at pile level), you may have to do some manual cleanup. This is very straightforward using the variety of manual point cloud classification tools within True View EVO.
The question naturally arises as to when to use photogrammetry and when to use LIDAR. Of course, if you already own a True View 3DIS, this is a moot point since our 3DIS systems do both. However, the real question here is when does one need to advance from pure photogrammetry systems (e.g. a Phantom 4 RTK) to LIDAR?
One obvious need are stockpiles that have been overgrown with vegetation. Photogrammetric point clouds “float” at the top of vegetation, causing the computed volume to be larger than reality. The extent of the error depends on the relative size of the pile compared to the height of the vegetation.
Coarse, Undulating Surfaces
A second common need are materials that have very coarse, undulating surfaces. Photogrammetry typically gives a rolling approximation to these surfaces. A good example (see Figure 2) is measuring the volume in log yards (feeder stock for pulp mills).
Other common examples include:
If you have a True View 3DIS, you can address all of the various volumetric scenarios since you have both photogrammetry and LIDAR. Of course, this does not mean that photogrammetry only is not a good solution. You just have to be careful to restrict it to those scenarios where photogrammetry shines. Regardless of your choice in sensor technology, we can help you with the software and technical support tools needed to be successful.