Project an LAS file with unspecified projection parameters

[gmcw49...@gmail.com]

Hi,

I have a set of V 1.2 LAS files with no projection specified.
From documentation and study and the coordinates I believe they are in WASP North, NAD83, Feet.

I am trying to project them into WASP South, NAD83, Feet.

I have tried various combinations of specifying the input and output projections, but the output LAS files are not ending up in the correct coordinates.

from fully specifying each --> '-sp83 WA_N -feet -elevation_feet -target_sp83 WA_S -target_feet -target_elevation_feet'

to using epsg codes --> '-target_epsg 32149 -epsg 32148'

have also tried removing any old info with the '-remove_all_vlrs' command.

the commands run without complaints ...

below is the lasinfo output from one of the files.

Any suggestions would be greatly appreciated!

Guy McWethy

lasinfo (161114) report for 47121E8101.las
reporting all LAS header entries:
  file signature:             'LASF'
  file source ID:             0
  global_encoding:            1
  project ID GUID data 1-4:   00000000-0000-0000-434B-313120202020
  version major.minor:        1.2
  system identifier:          'Watershed Sciences - ALS        '
  generating software:        'LiDAR Feature Extraction (LFEx) '
  file creation day/year:     158/2011
  header size:                227
  offset to point data:       282
  number var. length records: 0
  point data format:          1
  point data record length:   28
  number of point records:    4718709
  number of points by return: 3352290 1129469 236950 0 0
  scale factor x y z:         0.01 0.01 0.01
  offset x y z:               0 0 0
  min x y z:                  1352661.96 225599.61 292.26
  max x y z:                  1354666.81 230161.51 591.93
the header is followed by 55 user-defined bytes
reporting minimum and maximum for all LAS point record entries ...
  X           135266196  135466681
  Y            22559961   23016151
  Z               29226      59193
  intensity           1        253
  return_number       1          3
  number_of_returns   1          4
  edge_of_flight_line 0          0
  scan_direction_flag 0          1
  classification      1          8
  scan_angle_rank   -18         17
  user_data         115        131
  point_source_ID   144        153
  gps_time -13653718.183177 -13651672.344897
number of first returns:        3352290
number of intermediate returns: 272765
number of last returns:         3226927
number of single returns:       2133273
overview over number of returns of given pulse: 2133273 1817634 696220 71582 0 0 0
histogram of classification of points:
         4031820  unclassified (1)
          559849  ground (2)
          127040  keypoint (8)

[Evon Silvia]

I happen to be familiar with the dataset you're probably using, and if it's the one I'm thinking of I can confirm it's in WASP North, NAD83(HARN), and US Survey Feet. Note that this isn't the same as international feet, which is what you were using. Does it work as expected when you use the -survey_feet argument instead?

If not, I was trying to reproject onto some LCC projections with LAStools the other day and had the same problem. It appears that the pcs.csv file has ordinates stored in the dd.mm format, which is fine, but I was getting unexpected results whenever I tried to use the built-in definitions. In my particular case I was trying to reproject from UTM10 to Oregon Lambert (epsg 6557), and the only workaround I could find was to manually define the projection using -target_lcc and the corresponding projection definition, which got the expected results. I thought it was just user error on my end, but perhaps a recent update in LAStools broke LCC projections as they relate to Martin's pcs.csv file?

Evon

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[gmcw49...@gmail.com]

Thanks Evon!
That  worked ...   As long as I specify the input using the LCC parameters and Fully specify the output as State Plane NAD83, WA_S, target_feet

Is there a REAL difference between feet and Survey Feet when projecting these LAS files?

At least different enough that I should go back and make sure I projected into Survey Feet?  Oy ...

Gracias!

[Evon Silvia]

Sorry, fat-fingered the send key.

It'll make no measurable difference for elevations at the hundredths level until you're at a mile high or higher.

Evon

On Fri, Dec 2, 2016 at 8:57 AM, Evon Silvia <esi...@quantumspatial.com> wrote:

The difference between survey feet and international feet shows up in the 6th significant figure (1 international ft = 0.999998 survey ft). 

For example, the min/max coordinates in the file you sent are:

• Min: 1352661.96, 225599.61, 292.26 (US feet)
• Max: 1354666.81, 230161.51, 591.93 (US feet)

If I convert that to international feet, they're thus:

• Min: 1352664.67, 225600.06, 292.26 (int'l feet)
• Max: 1354669.52, 230161.97, 591.93 (int'l feet)

So you don't have to do the math in your head, there's the differences:

• Min: -2.71, -0.45, 0.00
• Max: -2.71, -0.46, 0.00

Therefore, for xy coordinates in the millions or hundreds of thousands (like yours, in WASP), it'll make a noticeable impact. Even moreso if you're in UTM coordinates or other state plane systems with larger false eastings/northings. Note that it'll make no measurable difference at the hundredths level until you're at a mile high or higher like in Colorado or on the taller Cascade peaks.

Evon

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[Evon Silvia]

The difference between survey feet and international feet shows up in the 6th significant figure (1 international ft = 0.999998 survey ft). 

For example, the min/max coordinates in the file you sent are:

• Min: 1352661.96, 225599.61, 292.26 (US feet)
• Max: 1354666.81, 230161.51, 591.93 (US feet)

If I convert that to international feet, they're thus:

• Min: 1352664.67, 225600.06, 292.26 (int'l feet)
• Max: 1354669.52, 230161.97, 591.93 (int'l feet)

So you don't have to do the math in your head, there's the differences:

• Min: -2.71, -0.45, 0.00
• Max: -2.71, -0.46, 0.00

Therefore, for xy coordinates in the millions or hundreds of thousands (like yours, in WASP), it'll make a noticeable impact. Even moreso if you're in UTM coordinates or other state plane systems with larger false eastings/northings. Note that it'll make no measurable difference at the hundredths level until you're at a mile high or higher like in Colorado or on the taller Cascade peaks.

Evon

On Thu, Dec 1, 2016 at 10:39 AM, <gmcw49...@gmail.com> wrote:

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[gmcw49...@gmail.com]

I did some empirical experiments.  Used same projection parameters in las2las, same file, but first I specified 'target_feet', and second I specified 'target_survey_feet".

the XY locations of the LiDAR points changed by 3.5 feet.

So the Answer is YES, it makes a significant difference.

Oy ..

Now we just need to figure out what to do about it ;)

Many Thanks!
Guy

On Tuesday, November 29, 2016 at 4:27:49 PM UTC-8, gmcw49...@gmail.com wrote:

[Evon Silvia]

Looks like LAStools is having a hard time finding its CSV with all the projection info. Have you looked in your lastools bin directory at the specified location (lastools\bin\serf\geo\pcs.csv) to make sure it's there? It's also possible that you might have it open in Excel, which would block other programs from opening it.

Evon

On Thu, Jul 13, 2017 at 12:41 PM, EDWARDS Jacob * DGMI <Jacob....@oregon.gov> wrote:

Hello,

 

I have been trying project Las points into EPSG 2992 from NAd83 Oregon State Plane North Feet, international feet.

 

The original data did not have projection information, I tried adding headers through Las tools in ArcCatalog. Points are showing up in proper location but the header information looks like this:  

 

 

I have been trying to add corrected VLR information but I keep getting this error:

 

 

I have tried using the –target epsg 2992 or 2269 command line but keep receiving the same geo\pcs.csv file error.

 

 

I am using the 6/28/2017 version of las tools.

 

Any help adding Oregon State Plane North header information into current points and then converting to epsg 2992 or 2269 -(NAD83 OGIC international feet)  would be very appreciated!

 

Jacob Edwards 

Oregon Lidar Consortium Coordinator

Oregon Department of Geology and Mineral Industries

800 NE Oregon Street, Suite 965, Portland, Oregon 97232

Direct: (971) 673-1557

Jacob....@oregon.gov

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