How to create a raster from some very large .xyz?

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01-02-2015 03:29 AM
SanderPaekivi
New Contributor II

Hello!

I've recently been working with some large .xyz data, about 1,2 gb worth. So far i've managed to get the points into ArcMap with the "ASCII 3D to Feature Class" tool. With a fraction of the data, i managed to create a tin and then use the "Tin to Raster" tool and got good results. ArcMap even processed the entire area to a tin file, about 2,7 gb, but was unable to display it (error about lack of memory) and even use it for the "Tin to Raster" tool.
I have thought about manually splitting the .xyz file to smaller portions and go with the "Tin to Raster", but there are still some issues i need to work around.
Firstly, the coordinates are depth points for a sea area around a large coast. Because of this i need to add some-kind of coastline reference to ensure that all interpolation reaches 0 z-value at the coast.
Secondly, if i partition the .xyz data to smaller groups, i'm afraid of getting artifacts at the breaking lines, which would ruin the end product (after merging the raster).

So far, i've been unsuccessful at finding a solution online.

Any help would be greatly appreciated!

All the best,
Sander Paekivi

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XanderBakker
Esri Esteemed Contributor

It sounds that you have LiDAR data, but in a less adequate format xyz. To use large amounts of LiDAR data as point features is not the most efficient way to handle this type of data. In case you also received .las data, use that instead and create a LAS dataset from it. Info here: ArcGIS Help (10.2, 10.2.1, and 10.2.2)

In case you don't have LAS file(s), you can convert your .xyz file to a .las file by using LAS Tools using txt2las.exe. Have a look at slide 6 from my presentation: Playing around with LiDAR, AHN2, Aerial Photography and LAStools in A… It is really easy...

Once you have the LAS dataset in ArcGIS, you can convert it to raster without any problem:

ArcGIS Help (10.2, 10.2.1, and 10.2.2)

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JamesFitzgerald
Occasional Contributor II

Hello,

First Question: Coastline reference. You could use an aerial image to drop several points by starting an edit session with the point.shp (with your XYZ and coordinates data). For your new points, you could calculate geometry for X field and Y field. Then, also populate the depth field with 0.

Another option or addition to above, you could run the interpolation and clip (Data Management) using a shapefile for you Area of Interest. You could also Extract by Mask after you run the interpolation using a shapefile  for area of interest.

Second Question: Maybe you could partition by creating an overlapping grid.shp or maybe just a grid.shp. If go this route you can create a grid, then export the points within grid.shp. You then do the analysis of interpolation on the points, merge, and check your data.

You could also use a smaller dataset- Not sure if need every point.

Hope this helps

James

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XanderBakker
Esri Esteemed Contributor

It sounds that you have LiDAR data, but in a less adequate format xyz. To use large amounts of LiDAR data as point features is not the most efficient way to handle this type of data. In case you also received .las data, use that instead and create a LAS dataset from it. Info here: ArcGIS Help (10.2, 10.2.1, and 10.2.2)

In case you don't have LAS file(s), you can convert your .xyz file to a .las file by using LAS Tools using txt2las.exe. Have a look at slide 6 from my presentation: Playing around with LiDAR, AHN2, Aerial Photography and LAStools in A… It is really easy...

Once you have the LAS dataset in ArcGIS, you can convert it to raster without any problem:

ArcGIS Help (10.2, 10.2.1, and 10.2.2)

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SanderPaekivi
New Contributor II

A big thanks for the replies! I'll put the ideas to test and post back with results asap.

SanderPaekivi
New Contributor II

Posting back!

The txt2las.exe worked great! Got the las to a dataset and from that the "Las to Raster" tool.

A problem remains however - the "Las to Raster" interpolated inside island areas aswell and i was unable to set a boundry or extent to which i wanted interpolation to be done.
The quality of the interpolation seems very good, but i see that the scale begins from -0,2 so it interpolates land at some part. It is small, but i'd like to get a more specific interpolation. Any tips on that would be greatly appreciated!

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XanderBakker
Esri Esteemed Contributor

There are many option when converting Las to raster. What options did you use (Binning, Triangulation)? Is it posible to include a screenshot to show what your result is (refering to the -0.2)?

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ferranferrer
New Contributor

If you prefer to perform tests with less data you can use

Subset Features (Geostatisical Analyst),

it allows you to get a % of original file.

For coastline, you can get values of 0 or near and transform to polylines and create a calc mask.

Probably you have to check the coastline with others data sources and imaginery.

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