Calculate Footprint Coverage

Use the Calculate Footprint Coverage option (Geosoft.uxo.gxnet.dll(Geosoft.GX.UXO.UceFootprintCov;Run)*) to calculate and shade the area covered by the footprint of the instrument.

Footprint Coverage dialog options

Current database	The current database name is displayed. Read-only. If you hover your cursor over the database name, the full path will display. Script Parameter: UCEFOOTPRINTCOV.INFILE
Survey boundary	Specify the survey boundary file in CSV or PLY format. Script Parameter: UCEFOOTPRINTCOV.PLYFILE
Cultural mask file	Specify the Cultural mask file in PLY format. Script Parameter: UCEFOOTPRINTCOV.CULTMASKFILE
Footprint
Shape	Use the dropdown list to select the footprint shape: Square Circle course resolution Circle medium resolution Circle fine resolution See Application Notes for more information. Script Parameter: UCEFOOTPRINTCOV.SHAPE
Size	Specify the size of the footprint. The length of a side for a square, or the diameter for a circle. See Application Notes for more information. Script Parameter: UCEFOOTPRINTCOV.FOOTPRT
Display coverage on a map	Specify how to display the coverage results, which can be displayed as: Show Process Log file Create a new map Use current map See Application Notes for more information. Script Parameter: UCEFOOTPRINTCOV.CULTMASKFILE
Plot Legend	If you selected Use current map above, the Plot Legend field become enabled. Select Plot Legend to enable the legend parameters. Script Parameter: UCEFOOTPRINTCOV.LEGEND
X Location (mm)	Specify the X location of your legend in millimetres, or click the Locate button to interactively select the location on your current map. Script Parameter: UCEFOOTPRINTCOV.LEGENDX
Y Location (mm)	Specify the Y location of your legend in millimetres, or click the Locate button to interactively select the location on your current map. Script Parameter: UCEFOOTPRINTCOV.LEGENDY

Application Notes

This quality control tool calculates the amount of the survey area/grid that has been covered given an instrument or anomaly footprint. At each survey data point, a gray-shaded polygon is drawn indicating the area covered by the footprint, individual overlapping footprints are combined to define coverage polygon(s), enabling you to see the area not covered by the survey. Blank areas represent areas not sufficiently covered by the instrument.

To calculate the percentage coverage, you need to know the survey boundary or grid corners. The survey boundary is a polygon file (PLY) defining the limits of the survey area. Alternatively, the grid corners can be used and are defined in the Survey CSV file (see Plan a UXO Survey). To cross reference the CSV file, the name of the database should be appended by the area/grid name. For example, for area/grid S1A001, the database should be named name_S1A001.gdb. The parts of the survey area/grid that are not accessible (for example due to buildings, other infrastructure or dense vegetation) can be defined using a cultural mask polygon (PLY) file. These areas will not be included in the percentage coverage calculations.

Select Footprint Shape and Size

For the shape of the footprint you can select the shape that best represents the footprint of your instrument. For Electromagnetic (EM) surveys (i.e. EM61, MetalMapper) a square likely best represents the footprint of the sensor. For other sensors, like a magnetometer, you can use a circle. There are three resolutions for the circle (polygon): coarse (10 side), medium (30 sides) and fine (100 sides). While a higher resolution does provide more accurate coverage result, it also significantly increases processing time, particularly for large areas.

For the size of the footprint, since (EM) instruments typically have a rapid falloff, and the footprint can typically be thought of as a function of the size of the sensor. For other sensors like a magnetometer, the size of the footprint, may be thought of as function of the detection radius for the smallest target of interest.

Results

The footprint coverage of the surveyed area will be calculated based on the specified shape and size. Also, if you provide a survey boundary, the area of the survey area/grid and the percentage covered.

You have two choices of how to output the coverage results:

• Only to the Process Log (text) file and Access Database, or
• On a map, showing the overall coverage polygon(s) on the current map or creating a new map.

It is recommended that you superimpose the cultural data on the shaded footprint prior to making any decisions on the coverage.

Coverage gaps can fall into into three different categories:

1. Coverage gaps that are within a predefined limit for the project,
2. Coverage gaps that are greater than a predefined limit for the project, and
3. Coverage gaps due to obstacles or inaccessible areas such as long fence lines, along buildings, under/near trees, etc.

For more information on identifying specific coverage gaps, see Calculate Infill Lines.

Access Database

When OK is clicked, the following information will be exported to the table Coverage_Table in the DID Access database if the database has been defined in Setup Parameters:

GX Parameter	Table Column	Comment
Input data file (GDB or XYZ)	Dataset_ID	Name of the Geosoft database
	Total_polygon_area	Area of polygon that circumscribed the data track lines, units of acres
	Area_covered	Area covered by the track lines at planned line spacing, units of acres
	Percent_Coverage	If an area polygon has been specified, and the coverage is calculated this entry is a simple ratio
	Coverage_Map_ID	Name of the map if reported using UX-Process Footprint Coverage tool