troubles changing point source id

[Clemens B]

Hi!

I am trying to change the point_source ID.

I used

lasinfo -i D:\Users\Masterarbeit\Gebiet1\25021.las -set_point_source_to 25021

and

lasinfo -i D:\Users\Masterarbeit\Gebiet1\25021.las -change_point_source_from_to 21 25021

The program runs correctly and in the cmd it looks like the values have changed, but when I start lasinfo to check, the old values are still there.

So I tried this command:

las2las -i D:\Users\Masterarbeit\Gebiet1\25021-o D:\Users\Masterarbeit\Gebiet1\25021neu.las -set_point_source 25021

It creates the new file and the point_source ID is changed correct.

I would not prefer using las2las to create a new file and just use the lasinfo command to change the exsisting file.  What am I doing wrong?

I also change the file source id and the file creation date with the lasinfo tool. They change correctly and also stay changed, only the point source is not working for me.

Thanks for your help!

Regards,
Clemens

Btw: Lastools is really awesome!

[Terje Mathisen]

Clemens B wrote:
> Hi!
>
> I am trying to change the point_source ID.
>
> I used
>
> lasinfo -i D:\Users\Masterarbeit\Gebiet1\25021.las -set_point_source_to
> 25021
>
> and
>
> lasinfo -i D:\Users\Masterarbeit\Gebiet1\25021.las
> -change_point_source_from_to 21 25021
>
> The program runs correctly and in the cmd it looks like the values have
> changed, but when I start lasinfo to check, the old values are still there.
>
> So I tried this command:
>
> las2las -i D:\Users\Masterarbeit\Gebiet1\25021-o
> D:\Users\Masterarbeit\Gebiet1\25021neu.las -set_point_source 25021
>
> It creates the new file and the point_source ID is changed correct.
>
> I would not prefer using las2las to create a new file and just use the
> lasinfo command to change the exsisting file. What am I doing wrong?

IMHO it would be really wrong for a program with the name lasinfo to
actually modify any data, but I see below that lasinfo does seem able to
modify just the header.

It is of course much safer to just touch the LAS header data, it can be
done in-place, while if you want to modify every point record, you
really cannot do so if the source file is in the LAZ format:

Modifying the point_source value, setting it to be the same for all
records, will of course also impact the compressibility of that data,
i.e. you pretty much _have_ to rewrite a new LAZ file in order to do so!

>
> I also change the file source id and the file creation date with the
> lasinfo tool. They change correctly and also stay changed, only the
> point source is not working for me.

You hould not do this either, the original source files should stay as a
read-only ultimate reference, making it possible to recover/redo any
intermediate processing stages.

Terje

>
> Thanks for your help!
>
> Regards,
> Clemens
>
> Btw: Lastools is really awesome!
>

> --
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- <Terje.M...@tmsw.no>
"almost all programming can be viewed as an exercise in caching"

[ka...@heidemann.us]

First, as a matter of terminology, if you are referring to the "ID" in the Header, that is the File_Source_ID.

Second, assuming the file is an original swath, or is comprised solely of points from a single swath, if you change the File_Source_ID in the header, you should (technically, must, to remain compliant with the LAS specification) also change the Point_Source_ID for each point in the file.

If your data is already cut into tiles created from multiple swaths ... this presents another problem altogether, as each tile should contain points referencing the original source file IDs that now no longer exist. You COULD undertake to change all the swath IDs, then correspondingly change all the point IDs  ... Original_ID --> Your_New_ID, but this will be arduous and very prone to error.   And although it is not required and rarely done, you should add a VLR to each tile file, listing which File_Source_IDs are present in each tile.

I second Terje's recommendation: File_Source_ID should never be changed in the original files, with this caveat:

It appears that you are attempting to prepend some digits to the existing ID. If this is consistently the case for the entire project, and the original ID will remain an immediately recognizable part of the new File_Source_ID, you could create new files with new File_Source_IDs AND Point_Source_IDs; verify that nothing else has changed, then delete the true originals, and call your new files "original".

Karl

[Clemens B]

Thanks for your help, guys.

Yes I am referring to File_Source_ID and Point_Source_ID and the file is an original swath. This is what I am trying to do, to fulfil the specifications of the LAS 1.1. The two IDs are wrong and must be changed.

The Original Files are save will be not altered.  I was trying to save disk space and time, because first it looked like that the lasinfo command was faster than the las2las.

I will now use las2las, but I think it’s confusing that the  -set_point_source_to  and  -change_point_source_from_to commands are included in the lasinfo_README.txt.

[Steven F]

Is there a lastools command that can change the point_source_id to match the file_source_id? I haven't found any in the documentation, but I may have missed something or it might be an undocumented feature. I've been using a batch script to do this, but I'll bet most people just use the -files_are_flightlines call which just assigns a unique number that isn't necessarily the file_source_id.

Steve

[Martin Isenburg]

Hello Steven,

good timing with your question. I was just about to release a new version (140207) and adding this functionality had been on my list for a while. It is now realized as the '- apply_file_source_ID' command line option (not exposed in the GUIs yet). Here you see it at work on seven strips for which i manually set the file_source_IDs to 32, 33, ... 38 with 'lasinfo' and the '-set_file_source_ID 32' option.

lasinfo -i strips_raw\LD*.laz -merged ^

            -apply_file_source_ID ^

            -nh -nv -nmm ^

            -histo point_source 1 

point source id histogram with bin size 1

  bin 32 has 2404613

  bin 33 has 2983331

  bin 34 has 2208166

  bin 35 has 2920460

  bin 36 has 2660474

  bin 37 has 838865

  bin 38 has 2423315

  average point source id 34.77

See 7 strips are those used in these tutorials after manually setting the file_source_IDs to 32, 33, ... 38 

http://rapidlasso.com/2013/04/20/tutorial-quality-checking/
http://rapidlasso.com/2013/10/13/tutorial-lidar-preparation/
http://rapidlasso.com/2013/10/20/tutorial-derivative-production/

So yes, a new LAStools version is out (140207). Especially lascanopy, lascolor, and blast2dem were improved a bit or had bugs fixed . 

Btw ... these seven raw strips contain some unknown values in the point source ID field as noted and visualized in the quality check tutorial linked above. Looking at the histogram below  it can be anyone's guess what value was stored there. Neither appears to be intensity nor height above ground.

Regards,

Martin @rapidlasso

=======================

lasinfo -i strips_raw\LD*.laz -merged ^

            -nh -nv -nmm ^

            -histo point_source 1 

point source id histogram with bin size 1

  bin 0 has 15140

  bin 1 has 12

  bin 2 has 25

  bin 3 has 7

  bin 4 has 6

  bin 5 has 10

  bin 6 has 7

  bin 7 has 3

  bin 8 has 5

  bin 68 has 1

  bin 69 has 2

  bin 70 has 2

  bin 71 has 5

  bin 72 has 13

  bin 73 has 1

  bin 74 has 12

  bin 75 has 1

  bin 76 has 3

  bin 78 has 1

  bin 79 has 3

  bin 85 has 3

  bin 86 has 2

  bin 87 has 1

  bin 104 has 9

  bin 106 has 1

  bin 109 has 2

  bin 110 has 2

  bin 111 has 1

  bin 114 has 9378

  bin 115 has 320660

  bin 116 has 69759

  bin 117 has 1334620

  bin 118 has 635791

  bin 119 has 1381394

  bin 120 has 2888980

  bin 121 has 494355

  bin 122 has 3322577

  bin 123 has 170535

  bin 124 has 1496400

  bin 125 has 382097

  bin 126 has 524478

  bin 127 has 602057

  bin 128 has 130055

  bin 129 has 762358

  bin 130 has 51463

  bin 131 has 578450

  bin 132 has 88324

  bin 133 has 233899

  bin 134 has 159642

  bin 135 has 55342

  bin 136 has 156088

  bin 137 has 13180

  bin 138 has 96163

  bin 139 has 19049

  bin 140 has 48167

  bin 141 has 24284

  bin 142 has 25758

  bin 143 has 41496

  bin 144 has 10266

  bin 145 has 51295

  bin 146 has 7435

  bin 147 has 39062

  bin 148 has 13545

  bin 149 has 20555

  bin 150 has 15474

  bin 151 has 5556

  bin 152 has 16774

  bin 153 has 2224

  bin 154 has 13597

  bin 155 has 2703

  bin 156 has 8160

  bin 157 has 5018

  bin 158 has 4384

  bin 159 has 7708

  bin 160 has 908

  bin 161 has 8294

  bin 162 has 1024

  bin 163 has 6276

  bin 164 has 1877

  bin 165 has 2666

  bin 166 has 2560

  bin 167 has 521

  bin 168 has 1182

  bin 169 has 139

  bin 170 has 471

  bin 171 has 51

  bin 172 has 394

  bin 173 has 125

  bin 174 has 154

  bin 175 has 256

  bin 176 has 132

  bin 177 has 634

  bin 178 has 132

  bin 179 has 552

  bin 180 has 225

  bin 181 has 407

  bin 182 has 273

  bin 183 has 238

  bin 184 has 476

  bin 185 has 138

  bin 186 has 714

  bin 187 has 152

  bin 188 has 665

  bin 189 has 343

  bin 190 has 432

  bin 191 has 571

  bin 192 has 159

  bin 193 has 773

  bin 194 has 159

  bin 195 has 784

  bin 196 has 310

  bin 197 has 519

  bin 198 has 694

  bin 199 has 206

  bin 200 has 931

  bin 201 has 78

  bin 202 has 696

  bin 203 has 164

  bin 204 has 441

  bin 205 has 277

  bin 206 has 124

  bin 207 has 493

  bin 208 has 59

  bin 209 has 478

  bin 210 has 92

  bin 211 has 292

  bin 212 has 252

  bin 213 has 207

  bin 214 has 295

  bin 215 has 70

  bin 216 has 443

  bin 217 has 42

  bin 218 has 314

  bin 219 has 135

  bin 220 has 215

  bin 221 has 237

  bin 222 has 130

  bin 223 has 404

  bin 224 has 38

  bin 225 has 373

  bin 226 has 66

  bin 227 has 339

  bin 228 has 171

  bin 229 has 175

  bin 230 has 356

  bin 231 has 115

  bin 232 has 566

  bin 233 has 60

  bin 234 has 607

  bin 235 has 182

  bin 236 has 578

  bin 237 has 266

  bin 238 has 613

  bin 239 has 374

  bin 240 has 1244

  bin 241 has 546

  bin 242 has 2350

  bin 243 has 1164

  bin 244 has 3702

  bin 245 has 2382

  bin 246 has 5724

  bin 247 has 2801

  bin 248 has 14107

  bin 249 has 906

  bin 250 has 1

  bin 252 has 10

  bin 253 has 5

  bin 254 has 12

  bin 255 has 101

  average point source id 123.416

[Steven F]

Thanks for adding this feature Martin. I finally had an opportunity to use it today. 

I just wanted to note to others that this call is not compatible with the "-cores" option. It took me awhile to discover this.

For example, this works: 

las2las -i *.las -apply_file_source_ID -odir ../ptsrc

But this:

las2las -i *.las -apply_file_source_ID -odir ../ptsrc -cores 4

will set the point source to 0.

[Martin Isenburg]

Hello Steven,

in the past few releases of LAStools (the latest one is 141218) the bug that las2las does not '-apply_file_source_ID'when run on mutliple cores with -cores 4 should have been fixed. Thanks for reporting this bug and please report all future miss-behaviours such as this one as well.

Regards,

Martin @rapidlasso

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