EZVOL Stockpile Volume Calculator

R.K. Martin & Associates, Inc.

8985 W. Jefferson Ave.

Denver, CO 80235

303-989-3455

www.rkmassoc.com

Updated June 2006

Summary:

The Ezvol program allows the user to calculate the volume of a stockpile, based on a survey of the base perimeter plus a survey of the surface of the stockpile itself. The perimeter points are used to form a TIN (Triangulated Irregular Network) which represents the base of the stockpile. The perimeter points plus stockpile points are used to form a second TIN, which represents the surface of the stockpile. The volume between the two surfaces is the volume of the stockpile.

The program displays the stockpile volume in either cubic feet or cubic meters. The user can enter a density factor for the stockpile material, and the program will display the total weight of the stockpile.

The user can display the survey points, the Delaunay triangles which form each TIN, a contour plot of stockpile thickness, or a 3-D solid mesh view of the stockpile. The 3-D display can be viewed at any of eight different angles, and at a range of vertical exaggeration scales.

Running Demo:

Install the demo by running SETUP_EZVOL. Use the default directories.

Once EZVOL has been installed, simply choose:

Start > Program > Ezvol Volume Calculator > ezvol

From the “File” pulldown menu, select “Import Trimble POS data”. Navigate to the POS_FILES folder directly beneath the Ezvol program. Select either of the two example files.

Once the file has loaded, the user may choose any of the six available graphical displays. For the 3-D wireframe display, the user can choose from one of eight viewing angles. The vertical scale can be varied to change the amount of vertical exaggeration in the display.

Note that the volume and density results are not displayed in the demo version. This is the only feature of the program that is disabled in the demo version. These values are displayed as zero.

To display stockpiles surveyed with enCampo equipment, the user can import enCampo format data by selecting “Import enCampo CSV file” from the “File” menu. Select one of the example CSV files located in the “enCampo_files” folder located directly beneath the Ezvol program. Use the “P” as the perimiter point designator, and blank “ “ as the stockpile point identifier.

To display stockpiles that are represented by XYZ data, select “Import from Separate XYZ data files” from the “File” menu. To display stockpile SP1, choose “sp1_perim.xyz” as the perimeter file, and “sp1_inside.xyz” as the stockpile points. To display stockpile STOCK, choose “stock_perim.xyz” as the perimeter file, and “stock_inside.xyz” as the stockpile points.

Description:

EZVOL is a simple software program that allows the user to calculate the approximate volume of a stockpile. It can also be used to estimate the volume of an excavated area, provided the original surface is fairly flat and/or uniform.

Disclaimer:

The accuracy of results obtained with EZVOL software depends on both the accuracy of the survey data, and also on the amount of survey data gathered for a particular stockpile. R.K. Martin & Associates, Inc. will not be held responsible for any losses or damages that result from the use of this software. The user is totally responsible for assessing the accuracy of the results. Results will not be accurate if the original surface on which stockpile material has been dumped was not relatively flat.

It is suggested that the user employ some other means to independently assess the volume of each stockpile that is evaluated with EZVOL. For example, it should be possible to calculate an order of magnitude number for a given stockpile by assuming an “ideal” shape for the stockpile. For example, the volume of a cone can be calculated as the area of the base multiplied by 1/3 the height. Thus, a stockpile that is the approximate shape of a perfect cone, 100 feet across at the base and 25 feet high should have a volume of approximately:

(3.1416 * 50 * 50) * (25/3) = 65,450 cubic feet

Input:

In the data collection software, select a coordinate system that is either feet (State Plane) or meters (UTM). Note: EZVOL cannot convert GPS collected coordinates from one system to another.

Currently, the program accepts a standard “POS” file or custom CSV file from the Trimble GPS software, or, alternatively, two separate “XYZ” text files containing Easting, Northing, and Elevation. The program also accepts comma separated output files from the enCampo software system. If you have a different survey system that generates point files, Martin and Associates will create a new interface for your files for a nominal charge.

The standard Trimble file POS contains survey point data for a perimeter traverse, plus one or more stockpile (or excavation) traverses. The user selects the units of measurement, density units, and density conversion factor.

The standard Trimble 5800 CSV file contains multiple records of comma delimited survey points. Each record contains the point identifier, northing, easting, elevation, and a blank code. Point identifiers should begin with one letter for the base perimeter, and a different letter for the stockpile points. For example, the perimeter points should be A1, A2, A3, etc., and the stockpile points should be B1, B2, B3, etc.

The separate “XYZ” files contain Easting, Northing, and Elevation values, one entry per line. There is an “XYZ” file containing the perimeter base survey points, and another “XYZ” file containing the stockpile survey points. This documentation assumes that the user has a Trimble GPS unit plus associated software. All subsequent instructions refer to use of this type of data.

The enCampo software CSV file contains index, easting, northing, elevation, and ID values, one entry per line. Perimeter points must have a unique ID. Internal stockpile points must also have a unique ID. All other points such as control points and origin point must be given an ID other than that used for the perimeter and stockpile points.

Output:

The program provides several graphical output options, as well as the following physical information in standard or metric units:

1) Base Perimeter Area

2) Stockpile or Excavation Volume

3) Stockpile mass

Data Gathering – Trimble 5800/ProXR Unit to Custom CSV file:

In the Trimble data collection software, select a coordinate system that is either feet (State Plane) or meters (UTM). Note: EZVOL cannot convert GPS collected coordinates from one system to another.

To use the program, a GPS survey of the stockpile or excavated area must be made. The survey is done in several steps. These steps are specifically for the new Trimble 5800 survey system, although the general outline pertains to all survey systems.

First, the base perimeter of the stockpile is surveyed. The user should “walk” the entire perimeter of the stockpile, being careful not to include any anomalous information (walls, fences, etc.). The identifier of the first point should be set to “A1”. As the perimeter points are taken, the unit automatically increments the number so that the points progress as A1, A2, …, A10, A11, …, A100, A101, etc.

Next, the surface of the stockpile is surveyed. The user should change the identifier from “Annn” to “Bnnn” before the first stockpile point is taken. This allows EZVOL to automatically differentiate between perimeter and stockpile points. If more than a very small fraction (1/2 of 1 percent) of stockpile points falls outside the limits of the perimeter, then a warning message is issued. Volume calculations made under these circumstances are probably not valid.

After the survey file has been transferred to the PC-based Trimble software system, all of the points are exported using the Custom choice for identifier, northing, easting, and elevation.

Example of Trimble 5800 custom CSV format that can be used with EZVOL:

A1,1202225.382,3136745.631,5089.327,

A2,1202225.348,3136745.673,5089.379,

A3,1202225.088,3136745.796,5089.279,

B4,1202218.154,3136730.726,5100.265,

B5,1202213.788,3136734.674,5098.772,

B6,1202215.849,3136733.589,5098.993,

Data Gathering – Older Style Trimble Units to POS file:

In the Trimble data collection software, select a coordinate system that is either feet (State Plane) or meters (UTM). Note: EZVOL cannot convert GPS collected coordinates from one system to another.

To use the program, a GPS survey of the stockpile or excavated area must be made. The survey is done in several steps. These steps are specifically for the older Trimble survey system using POS output, although the general outline pertains to all survey systems.

Next, the surface of the stockpile is surveyed. The user should provide as many survey location points as is practically possible. The more irregular the stockpile surface is, the more points that should be taken. Stockpile surveys can be split up into several data strings, if desired. There is no practical limit on the number of separate stockpile traverses that are made. There is one very important limitation that MUST be adhered to. All stockpile survey points need to be inside of the original base perimeter poly-line. If more than a very small fraction (1/2 of 1 percent) of stockpile points falls outside the limits of the perimeter, then a warning message is issued. Volume calculations made under these circumstances are probably not valid.

After the survey points have been gathered, they are then processed with the Trimble software to generate corrected coordinates. The Trimble software can also be used to edit individual points. For example, any stockpile survey points that were taken beyond the base perimeter outline can be deleted.

Finally, the base perimeter survey points and stockpile survey points are exported to a single “POS” file. This “POS” file is all that is needed by the EZVOL program. The position data must be exported using decimal degrees, and not degrees, minutes, seconds.

Example of POS format that can be used with EZVOL:

-90.948030504,39.373585446,423.277,693555.521,1289363.822,529.259

Example of POS format that CANNOT be used with EZVOL:

105 08 19.358418670 -, 40 3940.377439199+, 5117.513,3100234.817,1483927.794,5167.515

Data Gathering – enCampo Software:

To use enCampo Software, the only requirement is that the user choose a unique point identifier for perimeter points (Default is “P”, for perimeter), and a unique identifier for stockpile points (Default is “ “, blank, for stockpile points). If blank is used as the stockpile identifier, be sure that control points, origin, etc. are given a non-blank identifier.

After the survey points have been gathered and processed, they are exported to a standard comma separated (CSV) file. The file is free format, and contains data in the following order:

Point number, Easting, Northing, Elevation, Identifier

Data Gathering – Generic XYZ files:

If you can generate two simple X-Y-Z data files, one containing base perimeter points, and the other containing stockpile survey points, then you may use EZVol to calculate stockpile volumes.

Simply create the two files, and be sure the values are in the following order:

Easting, Northing, Elevation

The values can be separated by tabs, commas, or spaces.

Volume Calculation:

Calculating the stockpile volume is very straightforward.

First, start up the EZVOL software. Use the “Units” dropdown menu to choose whether the survey information is in Feet or in Meters.

This is dependent upon which GPS survey coordinate system is used. For “Units” in Feet the GPS coordinate system must be in feet, such as State Plane coordinates. For “Units” in Meters the GPS coordinate system must be in meters, such as UTM’s.

Note: EZVOL cannot convert GPS collected coordinates from one system to another.

Next, select the Volume option from the “Volume Options” dropdown menu. You may either calculate stockpile volumes or mined-out (excavated) volumes.

Enter the Stockpile Name, and User Name in the fields at the top of the main screen. If you need to calculate stockpile mass, then choose the density units and enter the density factor using the menu and input field in the upper right corner of the main screen. Note that a free conversion utility has been included with EZVol. Click on the Help menu, then choose “Launch Conversion Program.”

The date that the survey data was gathered should be set using the dropdown choices for Survey Date. MM=month, DD=day, YYYY=year.

Once the initial settings have been made, for Trimble data, select “Import Trimble POS data” from the “File” dropdown menu. Using the standard Windows file selection dialog, select the POS file.

For enCampo data, select the enCampo CSV file, and set the perimeter and stockpile identifier strings.

For XYZ data, you must first choose the XYZ file which contains the perimeter points, and then choose the XYZ file which contains the stockpile points.

After the file is chosen, the program automatically calculates area, volume, and mass. These values are displayed in the center right of the main screen. It is suggested that you first draw the perimeter points, and then all the points, to verify that you have successfully imported your data.

Any of six different graphical displays can be selected with the “Select Display Type” dropdown menu. Displays available include:

1) Thickness Contour Map – color-coded contour map of stockpile thickness.

2) Perimeter Survey Points – location map of perimeter survey points.

3) All Survey Points – location map of perimeter survey points plus stockpile survey points.

4) Perimeter Triangles – Map showing the Delaunay triangles that were constructed in order to calculate perimeter elevation points.

5) Stockpile Triangles – Map showing the Delaunay triangles that were constructed in order to calculate stockpile elevation points.

6) 3-D Wireframe Mesh – 3-D drawing of the stockpile, with color-coded elevation ranges. Note that the vertical scale may be exaggerated. The viewing direction of this drawing can be changed using the “3-D View Angle” dropdown menu.

Printer Output:

Hardcopy output of the calculation results plus the currently chosen display type can be generated using the “Print” option from the “File” pull-down menu. A preview of the output can be viewed by selecting “Print Preview”.

Methodology:

Volume calculation is performed using the following steps:

1) The perimeter points are used to construct a set of perimeter Delaunay triangles (also known as a TIN, or Triangulated Irregular Network). Delaunay triangles are a special set of triangles, which can be formed using the individual points, and are a generally accepted method for representing topography data. These triangles represent the stockpile base surface. There is an inherent assumption that the base area on which the stockpile has been dumped was relatively flat. If this is not the case, then the volume generated will not be accurate.

2) The perimeter points plus stockpile points are used to construct a second set of Delaunay triangles representing the surface of the stockpile.

3) An imaginary grid, on the order of approximately 200x200 squares to 400x400 squares, depending on the extent of the stockpile, is generated.

4) For the center of each grid square that falls within the base Delaunay triangles, an elevation is calculated. This calculation is straightforward. For whichever individual Delaunay triangle the grid point falls within, there are three known elevation values (the vertices of the triangle). From these points an equation can be generated for the plane containing these points in 3-D space. Using the equation of the plane, plus the easting and northing coordinate of the grid point, the grid elevation is calculated.

5) Repeat the calculation in step (4), but find the elevation of the stockpile for each grid point.

6) For each grid point, subtract the base elevation from the stockpile elevation to get the stockpile thickness.

7) Loop through each grid point, sum up the stockpile thickness values, and multiply this sum by the grid dimension (area). For example, if the sum of the thickness values is 1000 feet, and the grid chosen is 2 by 2 feet, then the volume is 1000 x 2 x 2, or 4000 cubic feet.