Control Point File Requirements and Formats

Control point files contain the surveyed coordinates of the control points you added while you were scanning or from a total station.

Control Point File Requirements

The control point file must meet the following conditions:

• Surveyed coordinates must be in a right-handed coordinate system.

• For each dataset, at least 3 control points need to be recorded and need to be contained in the surveyed control point file.

• All coordinate values must be in the metric system.

• Geo-referenced coordinates can be used.

• If you are using a local coordinate system (the origin is arbitrarily self-defined), then the origin should not be too far from the scanned site, ideally no more than a few kilometers. If the data is more than 20,000 meters away from your site origin, you will not be able to add your data to your NavVis IVION site.

Control Point File Format

The surveyed control points can be in .txt or .csv format.

CSV format

.csv files can be exported from e.g. Microsoft Excel. Make sure to use the following format:

CP00001, 1000.458, 1964.458, 0.1
CP00002, 1005.000, 2000.000, 0.2
CP00003, 1002.862, 2025.802, 0.3
# CP-wrong, 9002.212, 3025.432, 5.3. This entry will be ignored with "#" symbol

• Each line must contain the following values for each control point: ID (name), X, Y, Z (coordinates).

• Separate all values in each line with commas. Other delimiters cannot be interpreted by the software.

• Empty lines and data beyond the fourth column will be ignored.

• Exclude lines by adding # to the beginning of the line.

TXT format

A .txt control point file must be set up in the following format:

CP00001 1000.458 1964.458 0.1
CP00002 1005.000 2000.000 0.2
CP00003 1002.862 2025.802 0.3
# CP-wrong 9002.212 3025.432 5.3 This entry will be ignored with "#" symbol

• Each line must contain the following values for each control point: ID (name), X, Y, Z (coordinates).

• Separate the fields with a space.

• Empty rows and data beyond the fourth column will be ignored.

• Exclude lines by adding # to the beginning of the line.

IVION Processing Checks on Control Point File

After uploading the surveyed control point file, IVION will first perform an alignment check between the recorded control points and the uploaded surveyed control points.

The check includes:

• A notification if certain lines from the uploaded control point file cannot be recognized. The warning is marked in yellow.
  
  

• • A notification if certain control points from mapping cannot be found in the uploaded control point file. The warning is marked in red.
    
    
    
    

  Example: Control Point “3“ was captured, but not found in the uploaded file.

• Warning if certain control points have a large alignment error.

  • IVION will only show the warning in yellow, if the alignment error is over 10 meters.
    
    
    
    

    Example: Control point that has a large alignment error over 10m.

Left-/ Right-handed Coordinate System Check

In IVION Processing we need the control point coordinates in right-handed coordinate system, see Control Point File Requirements.

Sometimes, by swapping the left-/right-handed coordinate system (x & y columns), the alignment error will decrease. In this case, IVION will warn users, that the uploaded control point file could be in a left-handed coordinate system. For example:

Please double check on your surveyed control point coordinates, if you are sure the coordinates are measured in right-handed coordinate system, please press “Undo“.

If the surveyed control point was indeed in left-handed coordinate system, and the above warning showed up, then clicking Okay will let IVION processing automatically use the adjusted right-handed control point coordinates.

After the processing, you can download the corrected “Surveyed control points (.csv)“  directly from the processed data: