Terrain Datasets - Combining Data Sources of Multiple Resolutions

[JustinPreikschas]

Hi all,

I am trying to build terrain dataset using multiple data sources and I would just like to know the best practices. My study area is a long linear corridor spanning several states.

1) I have 1-meter lidar data available for most of the study area (with a terrain dataset already built), but I would like to supplement this data using the on-the-ground civil survey data that we have collected. Can I just load a new point dataset containing the civil survey points and expect good results? Many of the points fall within the bounds of the lidar data, but there are quite a few areas that fall outside the lidar data. Most of the points are ~100ft apart for general purpose use, and some areas have a full topo done with a 10-ft spacing.

2) I also have relatively low resolution break-lines from the civil survey data. Knowing that the break-line vertices can be upwards of 100ft apart, would adding this information to the lidar generated terrain hurt more than it would help? Perhaps I should erase the portions of the break-lines that fall within the lidar points and only use them with the terrain generated by the survey points outside of the lidar area.

3) As a further supplement to the lidar and civil survey data, I would like to add elevation information from the NED files. For my study area, most of it is 30m with some parts of 10m. I know that this does not compare with the lidar data, but it is better than "no data" regions for my purposes. What is the best way to accomplish this?

Sorry for the long-winded message, but processing this data takes a very long time and I would like to get it done in as few attempts as possible.

Thanks,
Justin

[JakubSisak]

Build a TIN not a Terrain Dataset if you want to be able to edit the final surface. Terrain Datasets are only useful for display not for editing or other analysis. (Future upgrades might bring more functionality)
Combining data from various sources might cause problems if elevation and XY position of common control points differs between the datasets.  You can of course combine the data using the best available data for each area.  Personally, i would avoid combining survey points in areas of intersection; in these cases i would use the better of the intersecting datasets, removing the less accurate points and replacing them with more accurate data. Your end result will only be as accurate as the input data and its accuracy.  Same goes for breaklines, depends on the accuracy of the breakline and your knowledge of the terrain and the input data.