Scanning Tip of the Week: Stockpile Contouring and Volumetric Analysis in Trimble RealWorks
Published Date November 8, 2022 AuthorJeff Turgeon
Welcome back for another Scanning Tip of the Week. This week we will use a stockpile dataset to review contours and volumetric analysis in Trimble® RealWorks®.
The previous few tips revolved around new project creation and preference options, providing some starting points for newer users. This topic deals with an analytical tool to compute volumes from point clouds or meshes. Many of the topics discussed in this article can be found in previous Tip of the Week entries. In such instances, links will be provided to assist in further detail.
First we start with our Imported, Sampled, and Registered dataset featuring a gravel stockpile.
For this example, our goal is to provide contours of the project site and a volumetric analysis of the stockpile. To create these deliverables, the point cloud must be segmented leaving only the ground and gravel stockpile. A quick way of doing this is to use the Topography-Based Sampling tool featured in a previous article.
The fences, signs, vehicles, light standards, and long grass are now removed and we can continue to the contour creation. Go to the Surfaces tab of the ribbon and select the Contouring tool.
Elevation ranges will be automatically provided based on the point cloud selected when opening the Contouring tool. These values can be changed if desired, along with the contour Interval and Tolerance.
Click the Preview button to generate contour lines using your specified definitions. The Principal Contours can then be defined and the individual contours can be displayed using steps 3 and 4 of the tool.
Next click Create to save the contours as a folder within the lower WorkSpace window. The following image shows the same contour process completed for just the stockpile.
Within the contour folder, each line can be made visible or not using the lightbulb icons. The colors can also be changed by clicking on the color square.
With the contouring completed, let’s move on to volumetric analysis of the stockpile. First, we will isolate the stockpile by using the Segmentation tool.
Choose the Polyline option and place vertices near the base of the stockpile when segmenting. Enclose the stockpile with your polyline, select In to choose the points within the polyline, then click Create save your selection as a new point cloud object.
With the newly created stockpile point cloud selected, click on the Volume Calculation tool on the Surfaces tab of the ribbon.
Next, Define a Plane using one of the options listed in the tool. For this dataset, the Pick 3 points on Plane option was used. Three points around the base of the stockpile were manually selected and a plane was fit to the defined points. A Resolution value can now be set. A smaller value will provide a more accurate result but will take longer to compute. Now click Preview to compute a volumetric analysis of the object.
Cut and Fill volumes are now provided within the step 3 window. Edits can be made to the object using the step 4 tools if required.
Once satisfied with the result, click the Report button to access additional information regarding the volumetric analysis. This report can be saved as an RTF file for future reference.
The process is now complete using a point cloud for volumetric analysis. Another option is to create a mesh first, then completing the volume calculation. This optional workflow continues after the segmentation step earlier in this article. Use the Mesh Creation tool within the Surfaces tab of the ribbon while selecting the segmented object in the lower WorkSpace window.
Similar to the volumetric analysis tool, a datum must be applied using one of the available projection options. For this stockpile, the Plane-Based Projection is selected and the Pick 3 points on Plane option is used. Next, set the amount of detail required using the slider bar and click Preview Meshes. Note: This operation can take a long time to complete. If meshing a large object containing millions of points, try downsampling the object prior to this step.
The preview mesh is displayed but shows some holes in the surface. Click Create to save your progress and allow for mesh editing.
With the mesh selected in the lower WorkSpace window, click on the Mesh Editing tool on the Surfaces tab of the ribbon.
This tool contains many options which are explained further in the Trimble RealWorks video here. For our purposes in this project, we are only interested in filling the holes in our mesh. Click the Fill Holes button to complete this task.
When satisfied, click Apply to save the edits, resulting with a mesh that’s ready for volumetric analysis.
Select the edited mesh in the lower WorkSpace window and follow the previous steps to compute the volumetric calculations.
As you can see below, the resulting volumes are similar to those generated using the point cloud object. Using the mesh creation step is up to you and the workflow needs for your project.
This Scanning Tip of the Week covered many tools within the Surfaces tab within Trimble RealWorks. Let us know how this article helped you in your scanning workflows. Until next time, keep on scanning.
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