Randy should also be aware of the difference between relative and absolute accuracy. Depending on what he needs one may be more important than the other. Following Toblers's first law, higher density data (if systematic errors are minimized) should have higher relative accuracy than lower density data (points closer together should be more alike than points further apart). But this does not mean that the points have higher absolute accuracy (as compared to surveyed orthometric heights). So if you are delineating wetlands you may be more interested in relative accuracy, but if you are measuring the height of those wetlands relative to sea level absolute accuracy may be more important.
The use of referencing Lidar point densities and accuracies to contour accuracies has always bugged me (as you well know :-) ). I have always hated having to summarize digital data using an analog scale. We only need to use contour intervals when we are talking in terms of accuracies on paper, not with digital data. So unless he is drawing polygons on a paper map he should not care about contour intervals. And defining Lidar data accuracies by the points classified as ground is in essence completely ignoring a major part of the source data- the non bare earth and that is unfortunately the part that I have always been most interested in.
Jason Stoker
July 7, 2012
Randy should also be aware of the difference between relative and absolute accuracy. Depending on what he needs one may be more important than the other. Following Toblers's first law, higher density data (if systematic errors are minimized) should have higher relative accuracy than lower density data (points closer together should be more alike than points further apart). But this does not mean that the points have higher absolute accuracy (as compared to surveyed orthometric heights). So if you are delineating wetlands you may be more interested in relative accuracy, but if you are measuring the height of those wetlands relative to sea level absolute accuracy may be more important.
The use of referencing Lidar point densities and accuracies to contour accuracies has always bugged me (as you well know :-) ). I have always hated having to summarize digital data using an analog scale. We only need to use contour intervals when we are talking in terms of accuracies on paper, not with digital data. So unless he is drawing polygons on a paper map he should not care about contour intervals. And defining Lidar data accuracies by the points classified as ground is in essence completely ignoring a major part of the source data- the non bare earth and that is unfortunately the part that I have always been most interested in.