In this video we show the process of processing multiple LAS files for each of three surveys measured on different dates for a site project.
Week 1 on Aug 10 2023 is the Existing Ground after vegetation has been cleared from the project
Week 2 on Aug 14 2023 is the post stripping survey after Topsoil has been removed and stockpiled
Week 3 on Sept 5 2023 is a progress survey after 3 weeks of dirt operations
Each survey comprises 4 scans (LAS files)
In the preparation stage we show how to
- Organize the data into Site Surveys
- How to separate the project grading area from the remaining area of the survey
- How to clean that project grading area to remove vegetation around the perimeter of the site and machines, vehicles, people and other noise from the grading area prior to modeling.
We then show you how to use the point Cloud Processor to thin the point cloud intelligently for each survey and build smoothed surface models that will be used for the volume calculations.
We then show you haw to compute the Earthwork volumes and compare the time to compute the results and the actual results, demonstrating the speed advantage of the Grid Volume method vs triangle method and also comparing two triangle computation methods that can also save you a significant amount of time (~35% of the time (20 mins vs 30+ mins)) at no accuracy cost in the results. The grid volume calculation can save you an additional ~63% of the time (<0.5 min) again for next to no difference in the overall results.
We then show the Volumes Manager Command and how you can use that to compute various volumes, store the results for later review, and create tables on the drawings of those results for plotting and drafting purposes.
In this video we recreate the Volume Reports and Tables based on new naming conventions for the Point Cloud Regions and Surfaces created from those Point Cloud Regions.
We also redefined the boundary areas for the project so that the total site grading limits can also be broken down into the 3 key areas for the Topsoil Mound, The Dirt Pile and the Cut / Fill Earthworks area. With these changes the reporting is simpler to understand and quantify precisely.
Note the Naming conventions for the Point Cloud Regions created are as follows
Survey Data - 01 - Aug 10
Survey Data - 02 - Aug 14
Survey Data - 03 - Sep 05
The 01, 02 and 03 designation in the middle of the name puts the survey into a sequence in the Point Cloud and Surface model lists. If you don’t use those the list is supported alphabetically which will not always give you the order you want. Since it is unlikely that you will do 100 surveys over the lifetime of these projects we stuck with a two digit field - if you think you will go over 100 then use a 3 digit field.
The Survey Data is the first field of the name - this designates that it is the residual data of the cleaning process - this contains the data outside the grading limits of the project as well ass any “noise data” inside the grading limits that you clean out e.g. for Machines, vehicles, people, piles of material etc. that do not represent the ground surface.
The date field is the Month and Day - if this is a multi year project then add 2023 to the end of the date. Note the use of two digit dates - this keeps the list in numeric order in the lists in the software.
Site Data - 01 - Aug 10
Site Data - 02 - Aug 14
Site Data - 03 - Sep 05
Same naming method as above - the Site Data is used for the data within the grading limits of the project that has been cleaned. This is the base data that will be used with Point Cloud Processor to create the reduced point cloud size that will be used for surface models.
PCP - Site Data - 01 - Aug 10 - Reduced
PCP - Site Data - 02 - Aug 14 - Reduced
PCP - Site Data - 03 - Sep 05 - Reduced
Same naming as above - PCP refers to the fact that these were created by the Point Cloud Processor and - reduced indicates that they are the reduced point cloud region. You could remove the Reduced part as PCP indicates the same thing. This would shorten the names some more and make them more manageable.
The Surface Models generated from the PCP point cloud regions carry the same name as the point cloud regions.
Note also I renamed the Layers of my project and named the lines / boundaries that I created to delineate the areas for the volume computations. I figured that I would want the following areas
- The site grading limits boundary. This will be used to compute the Topsoil Strip quantities (Aug 10 to Aug 14) and the Cut Fill Dirt Quantities (Aug 14 to Sep 05).
- The Topsoil Pile Boundary
- The Dirt Pile Boundary
- The Remaining Area (Site Grading Limits - Topsoil Pile - Dirt Pile Boundary areas).
With these delineated areas, it makes it easy to calculate the following numbers
- Topsoil Strip (Cut Qty across the whole grading limits)
- The Topsoil Pile (the Fill qty of the Topsoil Strip calculation for the entire grading limits, or the volume between Aug 10 and Aug 14 inside the Topsoil Pile Boundary.
- The Cut Fill Earthworks Volumes between Aug 14 and Sep 05 within the Grading Limits. This gives a Cut and a Fill Number. The Cut is in the Remaining Area where the pond is being excavated. The fill is split into the Dirt Stockpile and a small volume of Fill in the remaining area around the pond where you are constructing the Berm.
- The Shrinkage values are the deltas between the volume that you excavated vs the volume of fill - since you have no export, the fill is smaller than the Cut because the machines have been compacting the Topsoil or Dirt piles - this is creating a shrinkage of the available material. This applies to both Dirt and Topsoil. Note in this case the Topsoil cut was ~20000 m3 but in the Pile on Aug 14 it was ~17700m3 and then on Sep 05 it was ~12500m3 - so it continued to shrink after it was stockpiled based on the data provided.
With each week of survey you will do the following key steps
- Import the 4 LAS files that provide the point cloud scans for the site survey
- Select all of the data from those 4 scans only (turn off all other scans first) using Polygon Select and create a Point Cloud Region called Survey Data - 04 - Sep 14 etc.
- Use the Point Cloud by Boundary command to select the point cloud data from that newly created Survey Data point cloud region that lies inside the grading limits. Create a Point Cloud Region called Site Data - 04 - Sep 14 etc.
- Turn off the Survey Data point cloud region and then use polygon select to clean the edges of the point cloud region to remove vegetation and clean out machines, vehicles, piles of material and add those selected point cloud elements back to the Survey Data point cloud region for that survey.
- Run Point Cloud Processor on the Site Data point cloud region after it has been cleaned. This will create the PCP point Cloud Scans and point cloud regions and the associated surface model for that survey.
- Run volumes manager to compute the volumes of Cut / Fill for this survey against the appropriate prior survey. Note if you do the volume against the initial surface after topsoil strip you will get the total single movement of material over that period of time. If you do the volume between this survey and the prior survey, you will get the total single movement of material over that time period. Be aware that if material is moved 2x or more in that time period, and it was not surveyed, those additional movements of material will not be captured by this process
For example if I have my initial survey, then in the time before the next survey I dig a large hole (overex) and then backfill it prior to surveying a second time, I will not see that overex and backfill process in the numbers. If I survey the initial survey, then again when the hole has been excavated and then again when the hole has been backfilled, I will capture the hole excavation and backfill quantities. The volumes of dirt moved will be significantly different depending on how often and when you survey the site.
We hope you like these videos - they are about 90 mins long in total so break out some popcorn!