Interpolation with even spacing in x and y

[MatthewBray]

Hello guys,

Thanks for taking the time to read my question.  I'm new to arcGIS and trying to figure out the best way to perform a certain process.  Please let me know if there is a more intelligent way to perform these actions, and more importantly if you know how to get the data the way I want it.  I have one meter resolution LAS files, and I'm looking to put them into 2 cm resolution ASCII (x y z) files.

I have an LAS file that I bring in as a multipoint feature.  I then turn that multipoint feature into a raster so I can cut a certain part out of it using a shapefile.  I then convert the clipped raster back into a multipoint feature.  I then use spatial analyst to interpolate using the kriging method (which produces a raster).  I then turn the raster back into a multipoint feature.  Finally, I use feature class to ASCII to get the x,y,z coordiates out.

The problem is that the data has 2 cm resolution in the x direction, but 25 centimeter resolution in the y direction.  This produces strips of lidar points.  I'm attaching a picture of it if it is hard to understand what I'm saying without visually seeing it.  We are wanting evenly spaces points, so this will not work for us.  Does anyone know a method where we can do this and get the data we need?  Thanks again!

~Thefatalccidents

[MarcinGasior]

Firstly, what for do you need 2 cm spaced points when your data resolution in 1 meter. You wont get higher accuracy using such a spacing.

General workflow for lidar data is:
- convert LAS files to multipoint in geodatabase feature dataset
(- if you have 10.1 you can create LAS dataset directly from LAS file)
- create Terrain dataset (for example refer to Creating and using terrain dataset tutorial exercise)
- convert terrain dataset to raster with desired resolution and do something with raster (you don't need to convert it back to points and interpolate)

[MatthewBray]

Thanks for the reply.  I'm not exactly sure what you mean as far as the resolution, but maybe I'm not explaining myself very clearly.  Right now the data has a point every 100 cm.  I'm wanting the data to have a point every 2 cm in both the x and the y direction.  In the picture I attached the distance from each point is 2 cm in the x direction, but 25 cm in the y direction.

I'm going to try the workflow you suggested and see if the points come out evenly spaced in both directions.  Thanks again.

[RamB]

Hi

Have you considered using LAS Dataset to Raster Conversion tool ?
However, I do agree with the previous comment, that you will not gain much by reducing from 100cm to 2cm.

regards,

[MatthewBray]

Well, I have 10.0 so I don't think I have that feature.  I can turn the LAS into multipoint and then the multipoint into a raster easily enough though.  The real problem is when I turn the raster back into a multipoint to be exported to ASCII I get those weird lines.  This happens whether I interpolate the raster, or if I interpolate it while it is still a multipoint feature.  Does anyone know how to help? 😞   I've kind of hit a dead end here with my knowledge of arcGIS.  Thank you both for your replies, but like I said ultimately it still is interpolated in that weird line pattern.

[MatthewBray]

As far as turning it from a 100cm resolution to a 2cm resolution mesh, this is only a 50m x 100m area.  So I'll be gaining a lot of points needs to make a refined mesh from the LIDAR points.  Without refining it to this level the mesh would have huge triangles and would not work for our models.  I hope this brings why I'm wanting the high resolution to light.  It is ultimately so I can export a high resolution LIDAR file for meshing.

[RamB]

Well, I have 10.0 so I don't think I have that feature.  I can turn the LAS into multipoint and then the multipoint into a raster easily enough though.  The real problem is when I turn the raster back into a multipoint to be exported to ASCII I get those weird lines.  This happens whether I interpolate the raster, or if I interpolate it while it is still a multipoint feature.  Does anyone know how to help? 😞   I've kind of hit a dead end here with my knowledge of arcGIS.  Thank you both for your replies, but like I said ultimately it still is interpolated in that weird line pattern.

I dont know if my solution is scientific, but I give it a shot. Prepare a fishnet (available tool) of your desired resolution 2x2 for the entire extent you need. convert this fishnet to a polygon feature class and then convert the polygon to raster making sure the raster values are zero. Then using a raster calculator just add your solution raster to this new raster to get the values and then export it.

Second option is to create a new 'constant' raster (creating a constant raster is by a standard tool: constant value you can use being 1 or 0 for easier calculations) and get values from your solution raster by multiplication (if 1) or add (if 0) using a raster calculator.

this is not standard procedure but a small unscientific quick fix that may or may not work. 🙂

regards,