Changes between Version 2 and Version 3 of Processing/Lidarqcprocedure


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Timestamp:
Apr 30, 2009 9:54:20 AM (10 years ago)
Author:
mark1
Comment:

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  • Processing/Lidarqcprocedure

    v2 v3  
    3131=== Check overlap of neighbouring lines ===
    3232
     33The first thing to do here is to load up all lines into a viewer (or if runs out of memory load them up in pairs) and see how well they overlap in the horizontal plane. The Fugro viewer is probably best for this because it also allows Shapefiles to be read in. Check along features that cross between flight lines, for example, roads/field boundaries/hedgerows do they continue unbroken or are they offset between flight lines. Also, compare against the vectors (if available) for any gross offsets.
     34
     35The elevation between neighbouring flight lines must be checked too.  This can be done in various ways:
     36 * examining profiles over the overlapping regions: allows measurements of the height difference to be made (in Terrascan/Microstation)
     37 * Re-order points in Terrascan: reorder 'by elevation (Z)' and colour by flightline. This will ideally show a mix of colours in the overlap region. If only one solid colour is shown then this flightline is consistently higher than the the other.
     38
     39If the elevations are offset consistently between flight lines then this probably means an error with the calibration values (boresight or range correction). This should be corrected. If the offsets are random per flight line then the average offset per flight line should be noted but not corrected for (unless ground control points are available)
     40
    3341=== Check against OS vector maps ===
    3442
    35 
     43If not done in the above step then the flight lines must be checked against vectors (if available).