Net volume between DTMs

The name and location of the first DTM.

Note: The first DTM is assumed to be the upper surface.

Loads the Object ID and Trisolation ID drop-down lists with the objects and trisolations of the DTM.

In Surpac 6.6.1 and earlier versions, when you selected a DTM in the Location field, Surpac would load the DTM, validate it, and then load the Object ID and Trisolation ID drop-down lists. You could not interact with the form until the process was complete, which could be a long time for some large DTMs. Now, Surpac does not load the drop-down lists until you click the Refresh button, and validation does not occur until you click Apply in the form. Any validation errors are reported in the Message window.

Loads the Object ID and Trisolation ID drop-down lists with the objects and trisolations of the DTM.

• Selected: The volume calculation is performed within the nominated boundary string.
• Cleared: The volume calculation is not performed within a boundary string.

It is highly recommended that volume calculations are performed inside a boundary string. There are two cases when you would not want to use a boundary string: you are using only one surface, or you are using two surfaces that have identical surface boundaries but no intersecting triangles (coincident faces are acceptable).

Imagine that you are viewing a surface along the normal to the plane used during surface creation (that is, looking directly at the plane), the rules for clipping are:

• For a single segment string, "inside" the segment refers to triangles physically inside the segment.
• For a string with a single level of nested segments, "inside" refers to triangles physically inside the outermost segment but outside any inner segments.
• Multiple levels of nesting are handled by alternating "inside" and "outside" for each level of nesting. For example, if the black lines are segments of a string, the red areas are considered "inside" the string and the white areas are "outside":

No quality parameters are used in the report. The number of quality parameters identified on the Define quality parameters to use form will be zero.

The number of decimal places used for the results of the volume calculation.

Note: If you select the Report by elevation check box, to report the volume by elevation intervals, the elevations are displayed to one decimal place.

• Selected: The report includes additional information, such as the extents of the DTM and areas of elevation.
• Cleared: The report does not include any additional information.

• Selected: The report specifies the cut and fill volumes for the elevation intervals identified in the Range field.
• Cleared: The report does not specify the cut and fill volumes by elevation.

The search or weighting method.

• All points inside a triangle: Uses all points in each triangle, taking the mean value for the triangle.
• Radial search with inverse distance squared: Uses points within the search distance required to provide the number of points defined in the Minimum number of points field, and uses inverse square weighting for the values of these points.

• Selected: A new boundary string file is created with the report.
• Cleared: A boundary string file is not created.

• Selected: The modified DTM is saved with the name, and to the location, entered in the Location field.
• Cleared: The modified DTM is not saved.

The total for the first quality parameter.

A geometry problem has been encountered at the specified point. The recommended course of action is:

1. Recall the string file that you have chosen as the boundary tring into Graphics.
2. Move the point (at the coordinates given in the error message) by a small amount using the POINT MOVE function.
3. Save the string file.
4. Run DTM VOLUMES again.