Question

Problems writing to Esri ASCII Grid


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Hi,

 

 

I have pointcloud xyz-files that I want to write to Esri ASCII Grid-format.

 

I use a RasterDEMGenerator in the process with Interpolation method: Planar.

 

It is 2 meters between the points so I use X/Y cell spacing 2 meters.

 

But when I look at the resulting files it is a gap between them with no data (see image).

 

How can I connect them togheter?

 

 

 

 

If I process the two pointcloud-files at the same time then they will merge into one single perfectly shaped ascii-file.

 

But the problem is that I have 234 pointcloud-files with each 1,5 million points, and I have tried to merge them into a single ascii-file. It took about 80 hours for FME to process them, but still FME didn't manage to give me a resulting file because of some strange error.

 

 

Any suggestions please?

 

 

Cheers

 

Hans

3 replies

Userlevel 3
Badge +13
Hi,

 

My suggestion would be to process each file seperatly to produce a raster and them mozaiking them into a single raster.

 

By trying to process them all as a single file, FME will probably run out of memory at some point.

 

By rasterizing individual files, memory should not be an issue.
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Hi,

 

The problem is the NO DATA-gap (see the white space in the image) between the files, so mozaiking them togheter is not gonna solve my problem.

 

I have no problem in creating individual files, but when I open them togheter in ArcMap I dont want the NO DATA-gap between them.

 

 

As you can see in the image above, the green points are from one xyz-file and the red points are from another xyz-file. All points have a Z-value, so it is strange that the there is NO-DATA gaps in the resulting ASCII-files.

 

 

Am I missing something? :-/
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Safe Support suggested this workaround.

 

 

So to sum up, it appears that when you process one tile at a time you get gaps between the tiles, and if you try to process it all at once the amount of data is simply to vast to deal with, correct?

 

My suggestion would be to process your tiles 9 x 9. That is, process source tiles one at a time, but also include all their neighbors. Then at the end clip the 9 x 9 result with the original tile's extents and you shouldnt have any gaps.

 

 

I tried it and it solved my problem fairly. Instead of gaps I have overlaps now, but that is not a big problem.

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