PIX4Dsurvey's volume measurement tool measures the volume between a base surface (defined by a volume polygon) and the active point clouds. As a default, this method connects all the vertices and triangulates the volume above and below the base surface. It is possible to move the vertices vertically to a different altitude.

**IN THIS ARTICLE**

How to create a new volume

How to compute the volume

How to export a volume report

How PIX4Dsurvey calculates the Volume measurement

## How to create a new volume

- On the
*tools*bar, select the Volume measurement tool by clicking .Volume measurement selection.

- To draw a volume,
**left-click**on points in the 3D view. Right-click or press**enter**to complete the volume base polygon. - (Optional) To accurately mark the vertices, select the volume using the simple selection tool . The position of each vertex can be corrected in the 3D view, on the images, or using the vertex editor.
- (Optional) To assign a common elevation to the vertices of the volume base surface, first select the volume using the simple selection tool . Then, in the volume panel, click align vertices to choose how to align the vertices.

After drawing the volume, details about the volume measurement are displayed. More specifically:

- Name of the volume and name of the layer the volume belongs to. The name of the volume layer and color of visualization can be edited.
- 3D perimeter, 3D area, minimum and maximum elevation are displayed according to the drawn polygon.
Display of volume measurement details, after drawing the volume.

## How to compute the volume

Once the volume is drawn, in the *Measurements* section of the volume panel, click **Compute** to trigger the volume computation.

Compute the cut/fill volume measurements by clicking on **Compute** button.

After completing the volume measurements, the cut/fill volumes and errors are displayed.

Cut/fill volumes and errors are computed after completing volume measurements.

More specifically:

**Cut volume [units**Volume above the volume base. The volume is measured between the volume base and the surface.^{3}]:**Fill volume [units**: Volume below the volume base. The volume is measured between the volume base and the surface.^{3}]**Total volume [units**The total volume (cut + fill volume).^{3}]:

## How to export a volume or volume report

After computing the (cut/fill) volume measurements, the Volume report, the volume polygon and the 3d volume are available to be exported.

To export the Volume report:

- On the Menu bar, click
**File**, then**Export**. Alternatively, on the top right, click**Export**. The*Export*panel opens on the right. - In the
*Export*panel, select the output format (PDF, HTML, or CSV for volume reports. LandXML for the 3d volume. DXF, ZIP SHP, SHP, or GeoJSON for the volume polygon). - (Optional) Unselect the output Volume layers that do not need export.
- In the
*Destination*section, navigate to the path where the files should be saved. - Click
**Export**.

## How PIX4Dsurvey calculates the Volume measurement

PIX4Dsurvey calculates the volume as follows:

1. A new volume is drawn. For more information on how to draw a volume: How to create a new volume.

A volume is drawn.

The base of the volume.

2. PIX4Dsurvey projects a grid with GSD spacing on the base.

Projected grid on the base of the volume: This drawing is a sketch and does not depict the real dimensions of the grid. The grid has very small interval (the GSD).

3. For each cell i of the grid, its volume (V_{i}) is given by:

*V _{i }= L_{i }* W_{i} * H_{i}*

Where:

*L _{i }*= the length of the cell.

W

*the width of the cell.*

_{i}=*H*the height of the cell.

_{i}=The Length (Li) and Width (Wi) are equal to the project's GSD.

*L _{i }=W_{i }= GSD_{}*

The Height (H* _{i}*) is given by:

*H _{i} = *

*Z*

_{Ti }- Z_{Bi}*Where: *

*Z _{Ti}* = the terrain altitude of each cell at the center of the cell.

*Z*= the base altitude of each cell at the center of the cell.

_{Bi}Therefore, the volume *V _{i }*of cell i is given by:

*V _{i }= GSD*GSD* (Z_{Ti }- Z_{Bi})*

Volume of one cell of the base.

4. PIX4Dsurvey calculates 2 volumes:

- The Cut volume
*V*is the volume between the base and the 3D terrain when the terrain is higher than the base._{c}

*Cut volume = V _{C }*

*=*V

_{C}

_{1 }+ V

_{C}

_{2}+...V

_{C}

_{N}

Where:

*V _{C}*

_{1...N}= Cut volume for cell i..N

*The Fill volume**V*is the volume between the base and the terrain when the terrain is lower than the base._{F }

*Fill volume = V _{F }*

*=*V

_{F}

_{1 }+ V

_{F2}+...V

_{F}

_{N}

Where:

*V _{F}*

_{1...N}= Fill volume for cell i...N.

5. The Total volume is given by:

*Total Volume = V _{T }=*

*V*

_{C}+*V*

_{F}
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