I have two vector layers which I am having trouble lining up. First, I have a point layer that was developed a decade ago to sample information from Public Land Survey System records in Washington and Oregon State. Second layer I have is PLSS grid polygon layer recently downloaded from Bureau of Land Management. The points are not just nodes, but also were placed at various distances along the grid lines.

Spatial reference:

  • Point layer is projected in NAD83 / BC Albers, EPSG: 3005.
  • PLSS grid polygon layer is not projected, instead it has GCS North American 1983, EPSG: 4269

I have tried to project the grid layer to EPSG: 3005 and several others. Similarly, I have tried to reproject the point layer. Essentially, sampled points should line up with PLSS grid corners and other point placed along the grid lines, however all of my attempts to project each layer have yielded no desirable results, points are always off. I have tried OTF projection variations in QGIS and project function in ArcGIS Pro. Unfortunately, no documentation is available on development of the point layer, therefore I do not know whether previous PLSS layer used a different projection, but I would expect BLM PLSS layers to be the same to layer available a decade ago.

Please help to identify possible solutions, as the point layer contains a lot of valuable information which would take very long to replace or correct manually.

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  • It looks like the offset isn't the same for every point. Given that, it's hard to know what a "correct" answer would look like. You could measure all the offsets, take the average, and shift each point by that amount. But would that be "correct"? Or are you just trying to save the attribute data, and don't care so much about whether the exact locations are preserved? – csk Feb 1 '19 at 17:48
  • I am indeed trying to save the attribute data for the 7000 points placed on the nodes and the grid lines. – olekss Feb 1 '19 at 19:31
  • Then it sounds like a simple spatial join should do for the nodes. The challenge is figuring out where to place the points on the grid lines. Do you know where the points on the grid lines are supposed to be? Eg, are they at the midpoints between the nodes? Or are they at a specified distance from one node? – csk Feb 1 '19 at 20:02
  • One method would be to simply create a large number of points along the lines, eg by the points on geometry tool. Then spatial join the original point layer to the new point layer. – csk Feb 1 '19 at 20:03
  • @csk The points, unfortunately, do not have a distance from node attribute. Those points are placed at various lengths from the node along the grid, depending on the GLO record. – olekss Feb 1 '19 at 20:14

You can download the current WA/OR Cadnsdi Nodes from BLM as a Point layer called PLSSPoints. If you still require the old Points, there are 3 ways to align the old to the new data.

  1. Snap the old Points to the new Points.
  2. Spatial Join the old Points to the new Points.
  3. Attribute join the old to the new Points by PointID, such as "OR330160S0082E0_600300"
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  • Thanks, that's a good idea, except some of the points are not nodes and were placed at various distances along the the grid lines. I'll keep this in mind, but would like to find a solution to fix the entire layer. – olekss Jan 31 '19 at 16:15

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