How do I match two point layers (with different grids) to a common grid?

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10-27-2014 01:02 PM
AndyWitt
New Contributor II

Here's the problem I'm struggling with:

 

I have two different point layers, where points represent centroids of areas covering a stream segment. One layer (lets call it layer A) is coarser, with fewer point (each point represents a larger area), then layer B. There is no commonality between how the points are distributed, except for the boundaries. Each layer contains multiple attributes (ex. depth, velocity, areas). I want to create a common grid, but I'm hesitant about rasterizing this data, as I need to retain the multiple attributes.

 

I have tried converting each set of points to voronoi diagrams, then spatially joining layer A to layer B, and converting back to points, but there have been problems retaining area values required.

 

Also I have joined layer B's voronoi areas to layer A's points. This gives me layer B's areas in terms of layer A's points, but leaves holes in the coverage.

 

Ideally, I'd like layer A to fit within layer B, or have a new mesh fitted to the stream segment that both these layers can be applied to.

 

This is part of a time series analysis, where layer B comes from a model that tracks flow during the summer, while layer A comes from a model that can track winter under ice flow, which layer B's model cannot. This is part of a time series analysis, where layer B comes from a model that tracks flow during the summer, while layer A comes from a model that can track winter under ice flow, which layer B's model cannot. So at a certain point in my process, I'll need to switch from the summer points to the winter points.

 

Essentially, constant points need to be retained year round. The complexity comes from the switch in which model provides data, because when that switch occurs the geography of the points changes (due to how the models work differently from each other-beyond my control). Somehow the geography needs to stay the same though the models switch, whether that be to join one models point layer to the other, or to develop a new common grid.

 

Does anyone have suggestions for optimizing this process, or ideas I've failed to see/am not familiar with? I appreciate any help. I've attached some visual aids. Layer A, Layer B, and a possible goal I'm searching for.

 

 

I'm running ArcGIS 10.3 (prerelease) with Spatial Analyst.

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1 Solution

Accepted Solutions
AndyWitt
New Contributor II

I solved this problem using this process.

For Layer A or Layer B

1. Convert points to a grid with the point statistics tool. Point statistics uses a neighborhood analysis that can interpolate values from known cells to unknown cells.

2. Convert raster to point, which recreates vector points on a common grid.

3. Repeat steps 1-2 for each desired attribute. (This is where you have to bite the bullet a little bit)

4. Join all re-gridded vector point layers into one layer.

5. I also added X,Y coordinates for this compiled layer.

When your processing extent is standardized, and cell size of the created raster is the same, Layer A and Layer B can be transformed to perfectly overlapping, matching point grids.

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5 Replies
DanPatterson_Retired
MVP Emeritus

The points maker toolbox allows you to create sampling points on a grid (rotated or otherwise) with a fixed spacing.  Perhaps a spatial join to those would help rather than using a polygon or polyline grid

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AndyWitt
New Contributor II

Interesting! I'm downloading it now. I'll take a look and see how it works. Thank you for your response.

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AndyWitt
New Contributor II

Can you control point spacing in the points maker toolbox? Say you want all points to be 1meter by 1meter apart?

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DanPatterson_Retired
MVP Emeritus

Yes, but I can't remember...but I will post the documentation for the toolset on my blog in several minutes.  But I am pretty sure it does...Can't remember if you need to specify rows and columns or distance spacing either way if you know the extent, you can act accordingly.

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AndyWitt
New Contributor II

I solved this problem using this process.

For Layer A or Layer B

1. Convert points to a grid with the point statistics tool. Point statistics uses a neighborhood analysis that can interpolate values from known cells to unknown cells.

2. Convert raster to point, which recreates vector points on a common grid.

3. Repeat steps 1-2 for each desired attribute. (This is where you have to bite the bullet a little bit)

4. Join all re-gridded vector point layers into one layer.

5. I also added X,Y coordinates for this compiled layer.

When your processing extent is standardized, and cell size of the created raster is the same, Layer A and Layer B can be transformed to perfectly overlapping, matching point grids.

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