problems with conversion xyz to las

benjaminTh / bcal-lidar-tools

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problems with conversion xyz to las #4

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago

i tried to convert some xyz lidar files to .las format. Everything seems to 
work fine and new files are generated quickly. But when i try to view the 
result with the 3D LIDAR Viewer i get back an error message "variable is 
undefined: ASCIIPARAMS" or "triangulate: not enough valid and unique points 
specified". 

I'm using BCAL LiDAR Tools 1.4.2 in Envi 4.8 and my PC works with Windows XP Pro

How can i get out of this? Thanx. Flavio

Original issue reported on code.google.com by f.pogg...@gmail.com on 18 Dec 2012 at 1:28

GoogleCodeExporter commented 9 years ago

can you paste here the first few lines of your xyz lidar file?

Original comment by shrer...@isu.edu on 18 Dec 2012 at 2:04

GoogleCodeExporter commented 9 years ago

here they are:

 9.84852438  44.02637693    114.030 30 2
  9.84851866  44.02639615    111.400 10 1
  9.84852591  44.02640564    116.830 133 2
  9.84852695  44.02640887    113.500 82 1
  9.84851487  44.02641940    115.100 92 2
  9.84851131  44.02641475    117.340 128 2
  9.84849768  44.02641233    114.930 77 2
  9.84851168  44.02642267    117.040 61 2
  9.84852530  44.02643274    119.000 128 2
  9.84852042  44.02644988    119.340 87 2

Original comment by f.pogg...@gmail.com on 18 Dec 2012 at 2:14

GoogleCodeExporter commented 9 years ago

It looks like your XY are in degrees. When converting, in the "Ascii to LAS" 
conversion window, you have to change the projection from 'Arbitrary' to 
'Geographic Long/Lat'. This will ensure that proper header scaling are applied. 
I tested it with your data and  it works!

Original comment by shrer...@isu.edu on 18 Dec 2012 at 6:27

GoogleCodeExporter commented 9 years ago

Ok. Following your kind suggestion things got a little better but still it
doesn't work properly. Now the 3D Lidar viewer does open the file but what
I get is a vertical line of points: I desume that there's still some
trouble with the x-y coordinates of the point cloud. Reading the las header
file, I notice that there's a strange x and y scaling (1.0e-7). I then
tried to reproject the las file into planar coordinates (UTM-WGS84 Zone
32N): the converted file is now properly visualized! Nevertheless, it would
be useful not to be forced to convert the files into planar coordinates....

Original comment by f.pogg...@gmail.com on 19 Dec 2012 at 9:00

GoogleCodeExporter commented 9 years ago

Strange! I will look into it further. 1.0e-7 in the header is 0.0000001 which 
is the number of decimal places. You might also want to try ENVI's native Lidar 
visualization in ENVI 4.8 (32-bit) (File>Open External File>Las LiDAR>3D LiDAR 
Viewer).

Original comment by shrer...@isu.edu on 19 Dec 2012 at 2:01

GoogleCodeExporter commented 9 years ago

Version 1.5.0 has been released that allows you to manually specify scale and 
offsets during ascii to LAS conversions. This should take care of the issues. 
Remember, LAS format holds XYZ data in 
[http://www.exelisvis.com/docs/IDL_Data_Types.html long format]. If, after 
scaling, you have more digits than the format accommodates, you will need to 
apply proper offsets.

Original comment by shrer...@isu.edu on 20 Dec 2012 at 9:18

GoogleCodeExporter commented 9 years ago

Original comment by shrer...@isu.edu on 4 Mar 2013 at 7:06

Changed state: Fixed