e57 to LAS invalid points?

Ben Haugen

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Mar 18, 2014, 6:43:16 PM3/18/14

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I I recently exported some las files from e57 format using your tool, and am curious about the valid/invalid points:

What qualifies as an invalid point?
About 30% of several of the point clouds is removed as “invalid” unless I explicitly include them… why so many?
Is this a specific problem with e57 files or do other format conversions in LasTools do the same thing?
Do the invalid points represent real points or are they artifacts?
How might we include the time stamp from the e57 files in the exported las files?

For some background, I am a ME/PhD student at the Colorado School of Mines in Geological Engineering. My research is focused on detecting fine-scale displacements of the ground surface over large areas (embankment dams/levees and landslides). I need the .las format to do point-to-point temporal deformation measurements and have more than 1500 scans (used Leica C10) on the Ijkdijk project in the Netherlands. I am working with Ben Lowry (another PhD student at Mines) on this. I believe he is actually the one who initiated the creation of the e57 to las tool.

Martin Isenburg

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Apr 5, 2014, 2:07:40 PM4/5/14

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Hello,

Any people interested in the E57 format on this list? I wrote the e572las converter a while back and am not sure it is used much. How popular is this format? I occasionally get questions or feature requests for e572las but not often enough to warrant sinking a lot of time into this. Can someone chime in on Ben's questions?

Martin

Jonah Sullivan

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Apr 6, 2014, 6:48:56 PM4/6/14

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I think this blog post is an answer:

http://blog.lidarnews.com/the-s-word-standards?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+InTheScan+%28LiDAR+News%29

The ASTM standards group for the E57 format can't find enough people that are interested.

Jonah Sullivan
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Shane MacLaughlin

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Apr 7, 2014, 11:15:29 AM4/7/14

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Hi Martin,

We also put E57 support into our software at the suggestion of a user but we don't see it used that often. Richard Groom had a short article entitled LAS or E57? in Engineering Showcase a while back, and the consensus was LAS. See http://www.pvpubs.com/Events/archives/files/pdf/GW2013NovDec_p%2003.pdf

Best regards,

Shane

Michael Olsen

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Apr 7, 2014, 1:04:11 PM4/7/14

to last...@googlegroups.com, Gene Roe

Hi Martin and Lastoolians,

I'll offer a few thoughts as someone who works more with terrestrial LIDAR than airborne LIDAR.

Regarding E57, there are multiple aspects to be aware of that can be confused easily. Principally, the standards committee and the exchange format itself that was devloped by a subcommittee.

In Gene's lidarnews blog, he is referring to the main ASTM E57 committee which was charged with developing a standard for testing 3D laser scanners (accuracy validation, etc). That committee has not had much traction and has slowed down in recent years for a variety of reasons and arguments.

However, there was also the subcommittee that developed the E57 data exchange format which has been published and integrated into most major terrestrial laser scan packages (e.g., Leica Cyclone, Riscan Pro, TopoDOT). It is also being embraced by some open source efforts (Point Cloud library, CloudCompare). In my opinion it is a step in the right direction for terrestrial scanning, but there is still a lot of work to be done to make the integration seamless between various software packages. (You can see a chart that shows the level of integration here: http://www.libe57.org/products.html). This, however, is left to the vendors. It is also important to note that the main intent of this format is to be an exchange format, not a working format.

There has been talk of re-mobilizing the committee to develop a mobile LIDAR extension or integrating compression into the E57 format, but to my knowledge these are still a ways out. (I've cc'ed Gene so he can chime in, if necessary). The library is available here: http://www.libe57.org/ which is technically separate from the standard due to ASTM policies that they do not host software.

At the risk of being labeled as a heretic on the lastools list, I think there are some important benefits to the E57 format that aren't (yet) available in the las format. These include the inherent data structuring (very important for fast computations based on the acquisition patterns of terrestrial scanners, preserving calibrated imagery in the same file, and internal checksums are a few. Daniel Huber of Carnegie Melon wrote an article about its features. http://citeseerx.ist.psu.edu/viewdoc/download?rep=rep1&type=pdf&doi=10.1.1.208.3460 Obviously there are a lot of benefits to the las format as well, but I don't think i need to explain those to this group :)

As such, I think that an E57 to las converter is useful to help integrate airborne and terrestrial data easier. Right now there is a significant disconnect between these two "LIDAR communities" in a lot of ways. Whether it is worth Martin's time compared to the other tools he is developing, I don't know. It really comes down to how many people are using terrestrial data with these tools, which judging from the responses to this list probably isn't a lot. Several terrestrial packages do not support las output, so users often have to go to ascii and then to las. so the e57 could be a cleaner way. Most of these packages can import las, but there are some quirks when doing so.

Anyway, just thought I'd throw a few thoughts out there.

To answer Ben's original question about the invalid point, without a lot of thought my guess is that it refers to locations in the scan grid (read Huber's paper if you have questions about the data structuring) that did not produce a return (e.g., sky). To test i would suggest importing the las file produced with the converter back into Cyclone (i assume you have this from your post) and verifying the number of points and visually looking at the point cloud.

Michael Olsen
Eric HI and Janice Hoffman Faculty Scholar
Assistant Professor of Geomatics
School of Civil and Construction Engineering
Oregon State University
Email: michae...@oregonstate.edu
Phone: (541)-737-9327

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Mike Childs

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Apr 7, 2014, 1:14:10 PM4/7/14

to Martin Isenburg

Hello Shane,

Global Mapper also added support for E57 import last year at user request, but doesn't seem to be used much.

Best Regards,

Mike Childs
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acsferi

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Aug 6, 2015, 9:36:04 AM8/6/15

to LAStools - efficient tools for LiDAR processing

Hello,

>>>>>Any people interested in the E57 format on this list?

The ArchiCAD 19 in our office supports E57 format.

It would be convenient to use the LAS-GUI as a LAS to E57 converter.

Regards

Frank Acs

On Sunday, 6 April 2014 04:07:40 UTC+10, Martin Isenburg wrote:

Albert Godfrind

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Aug 6, 2015, 10:56:18 AM8/6/15

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You could just write the result as a shape file, then use GDAL to convert to S57 (via the ogr2ogr command).

A better long term solution would be for LAStools to use GDA/OGR for all its reading and writing from/to vector and raster formats. That would add a lot of flexibility.

And of course, also using proj4 would give it instant support for all coordinate systems on the planet (instead or requiring code changes whenever a new coordinate system needs to be supported).

Albert

On 4-Aug-2015, at 02:41, acsferi <acs...@gmail.com> wrote:

Hello,

>>>>>Any people interested in the E57 format on this list?

The ArchiCAD 19 in our office supports E57 format.

It would be convenient to use the LAS-GUI as a LAS to E57 converter.

Regards

Frank Acs

On Sunday, 6 April 2014 04:07:40 UTC+10, Martin Isenburg wrote:
Hello,

Any people interested in the E57 format on this list? I wrote the e572las converter a while back and am not sure it is used much. How popular is this format? I occasionally get questions or feature requests for e572las but not often enough to warrant sinking a lot of time into this. Can someone chime in on Ben's questions?

Martin

On Tuesday, March 18, 2014 11:43:16 PM UTC+1, Ben Haugen wrote:
I I recently exported some las files from e57 format using your tool, and am curious about the valid/invalid points:

What qualifies as an invalid point?

About 30% of several of the point clouds is removed as “invalid” unless I explicitly include them… why so many?

Is this a specific problem with e57 files or do other format conversions in LasTools do the same thing?

Do the invalid points represent real points or are they artifacts?

How might we include the time stamp from the e57 files in the exported las files?

For some background, I am a ME/PhD student at the Colorado School of Mines in Geological Engineering. My research is focused on detecting fine-scale displacements of the ground surface over large areas (embankment dams/levees and landslides). I need the .las format to do point-to-point temporal deformation measurements and have more than 1500 scans (used Leica C10) on the Ijkdijk project in the Netherlands. I am working with Ben Lowry (another PhD student at Mines) on this. I believe he is actually the one who initiated the creation of the e57 to las tool.

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Martin Isenburg

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Aug 9, 2015, 4:08:15 AM8/9/15

to LAStools - efficient command line tools for LIDAR processing

Hello,

You want a converter from LAS to E57? The LAS format is also a data exchange format and a much simpler one than E57. So I would suggest you ask the ArchiCAD 19 tech support to add an importer for the LAS/LAZ data exchange format. This can be easily realized usong either the LASzip DLL, Howard's older libLAS library, the LASlib library that powers LAStools or Howard's new PDAL library. In the meantime I suggest to try CouldCompare to convert LAS to E57 ... ?

Martin

On Aug 6, 2015 3:36 PM, "acsferi" <acs...@gmail.com> wrote:
>
> Hello,
>
> >>>>>Any people interested in the E57 format on this list?
>
> The ArchiCAD 19 in our office supports E57 format.
>
> It would be convenient to use the LAS-GUI as a LAS to E57 converter.
>
>
> Regards
>
> Frank Acs
>
>
>
>
> On Sunday, 6 April 2014 04:07:40 UTC+10, Martin Isenburg wrote:
>>
>> Hello,
>>
>> Any people interested in the E57 format on this list? I wrote the e572las converter a while back and am not sure it is used much. How popular is this format? I occasionally get questions or feature requests for e572las but not often enough to warrant sinking a lot of time into this. Can someone chime in on Ben's questions?
>>
>> Martin
>>
>> On Tuesday, March 18, 2014 11:43:16 PM UTC+1, Ben Haugen wrote:
>>>
>>> I I recently exported some las files from e57 format using your tool, and am curious about the valid/invalid points:
>>> What qualifies as an invalid point?
>>> About 30% of several of the point clouds is removed as “invalid” unless I explicitly include them… why so many?
>>> Is this a specific problem with e57 files or do other format conversions in LasTools do the same thing?
>>> Do the invalid points represent real points or are they artifacts?
>>> How might we include the time stamp from the e57 files in the exported las files?
>>>
>>> For some background, I am a ME/PhD student at the Colorado School of Mines in Geological Engineering. My research is focused on detecting fine-scale displacements of the ground surface over large areas (embankment dams/levees and landslides). I need the .las format to do point-to-point temporal deformation measurements and have more than 1500 scans (used Leica C10) on the Ijkdijk project in the Netherlands. I am working with Ben Lowry (another PhD student at Mines) on this. I believe he is actually the one who initiated the creation of the e57 to las tool.
>

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