A proprietary format is a file format of a company, organization, or individual
In contrast an open format is a file format that is published and free to be used by everybody.
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The GUID is infinitely useful.
It is guaranteed to be unique across the universe of all GUIDs.
You can generate one using any of a number of on-line GUID generators.
Remember, no one need know anything at all about the GUID so long as the same GUID is used for all files in a project.
Thus if a GUID is properly assigned to a project, all data within that project (all the way down to single points) can be uniquely identified.
Lewis Graham
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Since some of the JALBTCX surveys are done off-the-internet I can't use that link but I found an answer. Since I'm using Qt I can just use QUuid and convert to a QString (using QUuid::toString) to get the pieces. Now all I have to do is throw together a little app that they can use to generate one per survey (and of course keep track of it ;-)
On 05/12/15 10:04, Lewis Graham wrote:
Here is an on-line generator:
Second part – she must have duplicated a doppelganger’s GUID…..
Regards,
Lewis
Lewis Graham
AirGon LLC, small UAS Solutions
GeoCue Group
9668 Madison Blvd., Suite 202
Madison, AL USA 35758
01-256-461-8289
From: last...@googlegroups.com [mailto:last...@googlegroups.com] On Behalf Of Jan Depner
Sent: Tuesday, May 12, 2015 08:21
To: last...@googlegroups.com
Subject: Re: [LAStools] RE: [The LAS room] how to use project GUID of LAS header?
Thanks Lewis,
Now the next question is - where can I get a proper GUID generator ;-) Is there one in LASlib?
The second point though is covered here - http://news.nationalgeographic.com/news/2013/02/130220-russia-meteorite-ann-hodges-science-space-hit/
Cheers,
Jan
On 05/12/15 06:09, Lewis Graham wrote:
Hi Jan,
GUIDs are unique by construction – that’s the entire purpose of the invention of GUIDs. They solve the problem of uniqueness without the need for centralized arbitration.
If you create a GUID (using a proper GUID generator which, again, does not require a lookup of precreated GUIDs), the chances of creating a duplicate are less than the chance you get hit in the head by a meteorite.
We envisioned these as being used (in LAS) for managing data while still “near” the sensor. For example, I could tag a bunch of LAS files that came from the same sortie with a GUID and then tag the related metadata (such as the trajectory) with that same GUID. It is an optional field in the LAS header and can be freely used for project management schemes.
We did not envision the GUID as being particularly useful once data hit the exploitation phase (for example, a county government taking delivery of some LAS data). Once you have merged, at the tile level, a bunch of individual LAS files, the individual point tracking requires a local catalog (which can be stored in a VLR of the LAS file). I am not aware of any implementations of this.
Thus the GUID is primarily used in production management. It is particularly useful in multi-sensor, multi-contractor projects.
Regards,
Lewis
Lewis Graham
From: last...@googlegroups.com [mailto:last...@googlegroups.com] On Behalf Of Jan Depner
Sent: Monday, May 11, 2015 21:24
To: last...@googlegroups.com
Subject: Re: [LAStools] RE: [The LAS room] how to use project GUID of LAS header?
Lewis,
Exactly *how* is it guaranteed to be unique across the universe of all GUIDs. The implied question in the original post was, "where is the centralized system to lookup or assign globally-unique GUIDs". Please explain how a GUID is, to quote you, "properly assigned to a project". I can inadvertently (or on purpose for that matter) create a duplicate of any GUID that exists in any LAS file, therefore, it is *not* guaranteed to be unique across the universe of all GUIDs. Please explain how we can make sure that we aren't using something that was previously used by some other project. Can you provide a central clearing house for GUIDs? Can *anyone* provide a central clearing house for GUIDs? If so we would all like to know about it. I'd love to be able to label every file I create as USACE JALBTCX or Naval Oceanographic Office JALBTCX or NOAA JALBTCX but I don't know if I'll be duplicating something that already exists. The definition in the LAS v.1.4 specification is woefully inadequate.
V/r,
Jan Depner
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On Fri, May 15, 2015 at 10:54 AM, Martin Isenburg <martin....@gmail.com> wrote:
Hello,
okay. I am adding an option to lasinfo called '-set_GUID' that takes in a hexastring. That said, there is still an issue with endian-ness. The GUIDs seem to be defined as big endian [1] but the LAS specification states all fields are little endian [2]. Hence, I am not even sure the current way these strings are reported by lasinfo has been correct all these years.Are all GUIDs reported by lasinfo in the wrong byte order? I am admittingly much more knowledgable about grilling SQUIDs than being grilled over GUIDs ... (-;
The UUID is a 4-part entity, made up of a 32-bit unsigned int, a 16-bit unsigned int and another 16-bit unsigned int, and eight single characters. Each of the values should have the standard byte ordering for LAS files (little-endian) as far as I'm aware. A packed structure representation in C is:struct{uint32_t uidPart1;uint16_t uidPart2;uint16_t uidPart3;char uidPart4[8];};In PDAL we read each of the parts from the file separately, properly applying byte ordering as we go. Note that no byte ordering is necessary for part 4.--Andrew Bell
andrew....@gmail.com
Martin,In your example that sets the GUID, there are 5 fields separated by four '-' characters. The first three fields, highlighted in yellow below, map correctly to uidPart1, uidPart2, uidPart3 and are in the right byte order.
lasinfo -i fusa.laz -set_GUID F794F8A4-A23E-421E-A134-ACF7754E1C54 -nh -nv -nc
However, I'm confused about he last two fields (highlighted in green). How do these map to the 8 character string uidPart4? Since there are 16 hex digits, I assume each pair maps to one of the 8 uidPart4 characters in some way. Are these suppose to be utf-8 hex codes? If so, "A1 34 AC F7 75 4E 1C 54" appears to be invalid.How would I set uidPart4 to 'MyProj01', such that lasinfo reports the following?[...]project ID GUID data 1-4: F794F8A4-A23E-421E-MyProj01[...]LAStools version = 170828ThanksTom Jordan
After a close read of the spec, I'm getting the impression that it was originally intended to follow with the Microsoft-style of UUIDs, as described on the Wikipedia page.
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