Lab 7

Part 1 of 7: Introduction to Volumetric Analysis  

If you are in the construction, mining or agriculture industry, you know that monitoring stockpile volumes is crucial to the success of your work. Professional UAV operators such as myself are utilizing UAV mapping to study faster more cost effective ways to calculate, cut, and fill volumes while improving the accuracy of traditional measurement methods. With built in measurement, editor, and extraction tools available on photogrammetry and GIS softwares, UAV data has found its niche in environments that are unique, difficult to access, or hazardous to humans. Below are tutorials on how to calculate volumes with both Pix4D and Arc Map.

Throughout this lab different operations will be utilized. Some important concepts are listed below:

1. Create Extraction Clip Feature Class--------------------------------------------------Part 3 step 2
2.  Perform Extract By Mask------------------------------------------------------------------Part 3 step 12
3.  Perform Surface Volume Analysis------------------------------------------------------Part 3 step 17
4. Resample a DSM to 10cm-------------------------------------------------------------------Part 4 step 1

Part 2 of 7:Calculating Volumes with Pix4D

The purpose of this tutorial is to demonstrate how to calculate volumes of aggregate stockpile using Pix4D software. Assuming that you have the a Pix4D file open with data saved on lab 6, click (on) ray cloud and proceed with the following steps.

1. Under layers on the top left corner of the screen, click point cloud, but uncheck everything that is in the red box on Figure 1

   

   Figure 1: Model of Mine 

2. Next, navigate to the right hand corner of the map where you can see stockpiles. Refer to Figure 2. Note you will be calculating volumetrics for a small, medium and large stockpiles. To minimize ambiguity, refer to them as Pile A, Pile B, and Pile C.



Figure 2: Piles A, B, and C Identified in Pix4D

3. Now we are going to calculate the volume on  Pile A. To do this 
• Navigate to the Pile
• Click (on) View 
• Click (on) Volumes 
• Click (on) New Volume
4. Your courser will now turn into a point marker where you can left click points around the perimeter of the base of the stockpile. When doing this, make sure you click the around the flat elevation as shown in Figure 3.

   

   Figure 3: Front View of Pile A before Computing Data

5. Click (on) Compute (the stockpile will now appear red and green)
• Click (on) Copy
• Open up Microsoft Excel
• Click (on) Paste to enable your data to stay in a chart as shown in Figure 4



Figure 4: Side View of Pile A, and Copied Data to Excel

6. Now calculate the stockpile for Pile B and C by repeating steps 2-7. 
7. Add the results in the same excel document you will use these calculations to cross reference  calculations in Arc Map which will be discussed in Figure in the results section of this lab. While measuring, all three piles will appear similar to Figure 5.

Figure 5: Measurement of All 3 Piles Using Pix4D

Part 3 of 7: Calculating Volumes Using ArcMap

                                                                                                                                                              The purpose of this tutorial is demonstrate how to calculate volumes of stockpile using ArcMap software. Assuming that you have the ability to generate a dsm from the data in Pix4D, open it up and use the Hillshade tool to shade it. Once completed, refer to the following steps.

1. View your Hillshade in the main window (remember how to do this from previous labs) For your reference, the Hillshade should look like Figure 6. Labeled on the figure are Piles A, B, and C



Figure 6: Piles A, B, and C on Hillshade

2. On the Catalog pane of Arc Map, you are going to Create an Extraction Clip Feature Class in order to do this, pay careful attention to the Catalog. For more information about how the Extraction Clip Feature Class Tool refer to the Pertinent Links tab here:
• Right Click (on) wolfcreekgdb
• Click (on) New 
• Click (on) Feature Class 
• Refer to Figure 7 for clarity

  

  Figure 7: Step 2  With Sub-steps

3. Take a look at the UTM-Zone and do not trust it!
• Click (on) Import
• Go to wolfcreekgdb
• Click (on) Add
4. Now the correct UTM zone will appear in this case it is WGS_1984-UTM-Zone_16N
• Click (on) Next
• Click (on) Next
• Click (on) Next
5. In the New Feature Class box type in File_Name and set the Data Type as text
6. Right Below, type Cubic_M and set the Data Type as Short Integer Refer to Figure 8 and Click (on) Finish. 

   

   Figure 8: Fill Out Field Name and Data Type

7. As seen in Figure 9, Pile A appears as a Feature in Both your table of Contents and Arc Catalog

   

   Figure 9: Feature Class in Both Panels

8.  Click (on) the Editor Icon which looks like this
• Click (on) Start Editing
• Click (on) Create Features a panel will appear
• Click (on) Pile_A
• Click (on) Polygon
9. Left Click the area around Pile A the program will begin to cover the terrain as seen in Figure 10 Once you go around the entire Pile, double click 

   

   Figure 10: Editor Tool in Arc Map Surrounding Pile A

10. Repeat Steps 5-9 for Pile B and C and Click (on) Save
11. Once All piles are edited, click (on) Customize
• make sure 3D analyst is turned on
• Make Sure Spatial Analyst is turned on
12. Locate the Search Bar on the Right Hand Side
• Click (on) Extract by Mask a window will now appear
• to to learn more about what an Extract by Mask is click here 
13. Make sure your input raster is the appropriate dsm, and your Input raster or feature mask data is Pile_A as shown in Figure 11

    

    Figure 11: Ensure Appropriate Inputs

14. Name the new file Pile A_Clipped and save it to the wolfcreek geodatabase. Remember, its is highly recommended to save the Clip to the geodatabase!
• Click (on) Save
• Click (on) Ok
15. Turn off the shading, and turn off Pile A
•  you will now see the pile is clipped
• Click (on) the Information Icon and note the elevation to be around 293 as seen in Figure 12

  

  Figure 12: Clipped Pile A with Information Value

16. Repeat Steps 12-15 For Pile B and C
17.  Now we are going to perform a Surface Volume Analysis. In order to do this, go back to Pile A To learn more about what a Surface Volume Analysis does refer to the Pertinent Links Section which can be found here: 
• Click (on) Search
• Type in Surface Volume
18. For your input Surface, select PileA_clipped
19. Click (on) Open
• Name the File Pile A_info
• Make sure the Output Text File is correct
• Set the Plane Height to value found in the information tool seen in Figure 12
• Click (on) Ok refer to Figure 13 for clarity

  

  Figure 13: Step 19

  
  
20. Repeat Steps 17-19 For Piles B and C

Part 4 of 7: Re-sampling a Raster Data set to a new Pixel Size

For this skill you must be able to create an extraction clip, be able to extract by mask and be able to perform a surface volume analysis. To learn more about what Re-sampling a Raster Data set to a new Pixel Size does, click here: Once you have mastered that, (assuming you have data similar to this lab) refer to Figure 13 and follow the example tutorial. 

1. Locate your clipped file
• click (on) properties
• note the cell size as demonstrated in Figure 14 

  

  Figure 14: Cell Size of DSM

2. Although the cell size is 0.019, we want it to be 0.01 exactly. We want this because when we compare this to a DSM with aggregate removed over time, we need to make sure the pixel sizes match. Therefore, we are re-sampling a raster data set to a new cell size that way we can accurately calculate the different volumes of the stockpile. In my lab, I made 3 different clips for a stockpile on August 27th, September 30th and July 22nd. If you would like to see the figures for those, go to Part 5. if you would like to see the method how this was achieved, follow the rest of the steps.
3. Go to the data search engine on the right hand side of your screen and type in resampling
• specify the input raster of your clipped file 
• make sure the output data set is in a geodatabase and when saving, name the file with a 10cm at the end of it to distinguish the raster
• Click (on) Save
• For your X and Y values, type in .10
• Click (on) ok 
• Refer to Figure 15

  

  Figure 15: Resampling Tool

Part 5 of 7 :Discussion Volumetric Results Using Pix 4Dmapper and Arc Map

In Figure 16 are volumetric calculations obtained from Pile A, B, and C using Pix4Dmapper. As you can see Pix4D displays different values compared to Arc Map pictured in Figure 17. Although the class is not completely certain why, it is believed that Pix4D's calculations are incorrect because the spherical camera used on the UAV was not supported for the Pix4D, the terrain area was poorly defined, or the parameter selections were off. As a result, this software processed incorrect data.

Nevertheless had Pix4D calculated the data correctly, someone knew to calculating vol-metric  data would have less trouble learning to use Pix4D compared to ArcMap. Although ArcMap has more to options and tools to siftthrough data with, it takes a long time to learn, and online tutorials in English are not easy to find. Nevertheless, further research and learning about these two softwares will be covered in this class.

Figure 16: Volumetric Calculations used in Pix4Dmapper

In Figure 17 are the calculations obtained from Pile A, B, and C but used with Arc Map

Figure 17: Volumetric Calculations used in Arc Map

 Part 6 of 7: Analyzing the Volume of a Stockpile Over Time

In this section, we were tasked with calculating volumetric data of a stockpile from July22nd through September 30th. (see dates in key metadata) Figures 18, 19, and 20 display maps of the three time periods. Notice the the volume listed three lines below the map title. As you can tell, there was an overall net loss between July and September but you can see that there was a gain between July and August. When comparing these maps, note that I could have snipped less elevation around the pile which would have resulted in more accurate results. Nevertheless these calculations demonstrate the capability a UAS has for taking large stockpile measurements.

Figure 18: July 22nd

Figure 19: August 27th

Figure 20: September 30th

Part 7 of  7 Conclusion

Throughout this lab, we utilized several geoprocessing tools along with two geodatabases in order to construct, compare, and contrast stockpile calculations. In figure 21, I created a map showing elevation exaggerations of stockpiles A, B, and C which can be referenced in Figure 6 as well. To wrap up the rest of the exercise I included a video of how UAS is applied to stockpile measurement here: 

Figure 21: Map of Wolfpaving Stockpiles A, B, and C