Volumetric's

We are going to calculate the volume of an aggregate pile that was created during a dredging operation, then we will be utilizing several new tools within ArcPro. We will be working with two different datasets, the first is Wolfpaving and the second is Litchfield which we've already used in a previous post. The three main tools that were going to use is:

• Extract by Mask: Extracts the cells of a raster that corresponds to the areas defined by a mask. If the mask is a feature, it will be converted to a raster internally using cell size and cell alignment from the input raster. For Wolf Creek, I used the dsm input with the Pile1 cut out I made over the pile.
• Resample: Changes the spatial resolution of a raster dataset and set rules for aggregating or interpolating values across the new pixel size. The cell change can be changed, but the extent of the raster dataset will remain the same.
• Surface Volume: Calculates the area and volume if the region between a surface and reference plane. Applying a Z factor ensures the accuracy and volume calculations when using values are expressed in a different unit. This operation will create an output text file that will display the generated results. For this project I used my extracted file with a z factor of 1 and plane height 293 to calculate my volume.

To begin, we are going to be working with the Wolfcreek dataset. The coordinate system is WGS 1984, the unit of measure is meters, and the GSD is 2cm. First, we want to create a polygon feature class and the extract by mask tool operation to clip out the aggregate piles.

• Right click wolfcreek.gdb in the catalog and add a new feature class, I named mine Pile1
• Use the polygon tool to create the area you want to clip out which is the piles
• Use the extract by mask tool to clip out the area using these parameters:
• Input Raster: WolfPaving_AT319demo_dsm
• Input Raster or Feature Mask Data: Pile1
• Output: Extract_Wolf1

Figure 115: Wolfcreek After Extraction

Next we will use the surface volume tool to generate the volume for each of the raster clips.

• In the geoprocessing pane, search for surface volume and set the following parameters:
• Input: Extract_Wolf1
• Reference Pane: Above
• Plane Height: 293
• Z Factor: 1

Once this finishes, it will create a table that gives you elevation surface information.

Figure 116: Wolfcreek Elevation Surface Information

Now that we have our piles clipped out and we have our surface elevation data, I created a cartographic map with and inset for the piles:

Figure 117: Wolfcreek Stock Pile Volumetric

The next phase is that we are going to engage in volumetric using temporal datasets. When calculating data sets over a temporal period, you should keep the sensors, altitude, and spatial accuracy the same because you need the data to be consistent. You need to have apples to apples when comparing over time so you can get an accurate analysis over time. This dataset has data collection from three different dates, and the original pixel size is 2cm. We are going to resample these these datasets to 10cm and 100cm. We are going to look at the changes in volume after they are resampled. First is to engage in a resample operation:

• In the geoprocessing pane, search for Resample and use the following parameters:
• Input: Whichever set you want to start with
• Output: ...10cm_resample
• XY: 0.1
• Resampling Technique: Bilinear
• Next we will use the same extract by mask tool that we used above on the Wolfcreek for this Litchfield dataset. We will later use use these to create maps that are presented at the bottom of this page.

The reason we set the X and Y size to 0.1 instead of 10 is because you have to remember that the units are in meters. So if we want to resample to 10cm, then you would want to put 0.1. Follow that same operation for each of the three different dates the data was collected, then do the exact same operation but resample to 100cm. In order to resample to 100cm, you would want to set the X and Y size to 1. The table below shows the different volume amounts compared to the date the data was collected and the resampled pixel size.

Date	Coordinate System	Pixel Size	Volume
20170704	WGS 1984 UTM Zone 15N	2cm	12082.062501
20170722	WGS 1984 UTM Zone 15N	2cm	32444.772375
20170827	WGS 1984 UTM Zone 15N	2cm	83784.956743
20170704	WGS 1984 UTM Zone 15N	10cm	20856.142707
20170722	WGS 1984 UTM Zone 15N	10cm	58612.006399
20170827	WGS 1984 UTM Zone 15N	10cm	83773.645472
20170704	WGS 1984 UTM Zone 15N	100cm	20528.903631
20170722	WGS 1984 UTM Zone 15N	100cm	42026.265151
20170827	WGS 1984 UTM Zone 15N	100cm	83595.554446

0. Volumetric analysis calculates the area and volume of the region between a surface and a reference plane. Use the Z factor to ensure the accuracy of volume calculations when the surface Z values are expressed in a different unit of measure than the XY units. There are two directions for the reference plane to measure the results. Above and below the plane, Volume and area calculations will represent the region of space between the specified plane height and the portions of the surface that are above or below the plane. Then the results will be displayed in a text file.

   It is important to calculate the times when engaging in this analysis because the different pixel sizes will affect the amount of time it takes to run the process. If we were working with a much larger data set, it would take a lot longer to process. These are things you will need to think about when in a time crunch. Hardware can also influence this because if you don’t have sufficient hardware, it can make the process much slower. If your CPU isn’t strong enough, it can make the analysis take a lot longer. Cloud based options would be a good idea because it makes it easier to store and access your data.

   Resampling comes into this because it allows you to change the pixel size which will affect the resolution and the amount of time it takes to analyze. You can have good resolution but the time it takes to process will be longer. The tradeoff is you could have worse resolution but a faster processing time. Beyond calculating volumes at a mine, another application for this process is construction or architecture. You could use this data to determine the right place to put a building or anything you would want to design and build.

   

   Figure 118: Litchfield Volume Analysis at 2cm

   
   

   

   Figure 119: Litchfield Volume Analysis at 10cm

   
   

   

   Figure 120: Litchfield Volume Analysis at 100cm