Las File Analyst Edit Tab

Here, the user may manually input values and create edits for the LAS file header that the Analyze tab may not flag as an error. The user can manually write file header information, repair erroneous point counts, etc. These actions help to repair files that may have been rejected by recipient organizations for LAS compliance issues. The Edit Action(s) will run when the Edit button is clicked on the main LAS File Analyst dialog.

GPS Time Conversion

The "Convert GPS Week to GPS Standard Time" function allows users to convert the GPS timestamp on all points from GPS Week Seconds to GPS Standard Time.

GPS Week Time – Timestamps on points are the number of seconds that have passed since GPS Sunday midnight of the week in which the data was collected.

GPS Standard Time – The number of seconds that have passed since GPS Sunday midnight January 6, 1980 in which the data was collected minus 1x10^9 (1 billion) (Adjusted Standard GPS Time).  The offset moves the time back to near zero to improve floating point resolution.

Note: GPS Timestamps are only supported on LAS Versions 1.2 and higher.  Also, Point Data Record Formats (PDRF) 0 and 2 do NOT support GPS Timestamps.

In order to convert to GPS Standard Time the user must specify the GPS Week Number in which the data was collected. The LAS File Analyst Options dialog allows the user to either key-in the GPS Week Number OR use a Date Picker to select the week in which the data was collected.

After running this Edit the user may verify the conversion by checking  a couple of columns in LAS File Analyst. Here the first two files have been converted.

Set Source Point ID

Absolute – Set every selected file to the set number (they will all be the same if more than one are selected).

Offset by – Offsets the current Point Source ID of a point by the value specified (positive or negative).

Auto-Increment Starting at -  Set the first row (file) to the value of the parameter then increment each additional row by 1.

Note: The LAS File Analyst Options Dialog settings will persist between sessions.