Changeset 835 for trunk/doc/las2las.txt

Timestamp:

08/18/08 02:18:30 (4 months ago)

Author:

hobu

Message:

a solution (not great) for turning the reStructured text documents into man pages. Requires the developer have Python and docutils installed

Location:

trunk/doc

Files:

• . (modified) (1 prop)
• las2las.txt (modified) (5 diffs)

trunk/doc/las2las.txt

@@ -5 +5 @@
 :Author: Martin Isenburg
 :Contact: isenburg@cs.unc.edu
+:Author: Howard Butler
+:Contact: hobu.inc@gmail.com
 :Revision: $Revision$
 :Date: $Date$
@@ -14 +16 @@
     :backlinks: top
 
-las2las reads and writes LIDAR data in the LAS format while modifing its 
-contents. Examples are clipping of points to those that lie within a 
-certain region specified by a bounding box (-clip), eliminating points that 
-are the second return (-elim_return 2), that have a scan angle above some 
-threshold (-elim_scan_angle_above 5), or below some intensity 
-(-elim_intensity_below 15).  Another typical use may be to extract only 
-first (-first_only) returns or only last returns (-last_only). Extracting the
-first  return is actually the same as eliminating all others 
-(e.g.-elim_return 2 -elim_return 3, ...).
+Description
+-----------
 
+`las2las` reads and writes LiDAR data in the ASPRS LAS 1.0 and 1.1 formats while 
+modifying its contents. While `lasinfo` can do a few simple operations like 
+updating header information, more drastic changes, like removing points or 
+altering values, will require `las2las`.  `las2las` is expected to be used for 
+modifying single files at a time, and all `las2las` operations require multiple 
+read passes through the points.   Some examples of operations `las2las` can be 
+used for include:
 
-Example usage
--------------
+* clipping of points to those that lie within a certain region specified 
+  by a bounding box (--clip)
+* eliminating points that are the second return (--eliminate_return 2), 
+* eliminating points that have a scan angle 
+  above some threshold (--eliminate_scan_angle_above 5)
+* eliminating points that have an intensity below some 
+  threshold (--eliminate_intensity_below 15)
+* extracting only first (--first-only) or last (--last-only) returns
+* changing the format from LAS 1.0 to 1.1 or vice versa
+* eliminating points of a given classification (--eliminate class 2)
 
-::
+`las2las` is a port of Martin Isenburg's `las2las` utility from `LASTools`_ 
+to the libLAS library.  For the most part, it is unchanged from Martin's 
+utility except for a few differences:
+
+* Text output describing the operation(s) is only provided when the --verbose 
+  switch is provided.
+
+* Provides some point validation
+
+* Variable Length Records (VLRs) are carried forward by default.
+
+* Supports format (1.1->1.0 & 1.0->1.1) conversion.
+
+* GNU-style arguments and switches (although most of the switches used by 
+  Martin's utilities should continue to work).
   
-  $ las2las -i in.las -verbose
-
-lists the value ranges of all the points (similar to lasinfo)
+Usage
+-----
 
 Clipping with a rectangle
--------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~
 
 ::
 
-  $ las2las -i in.las -o out.las -clip 63025000 483450000 63050000 483475000
+  $ las2las --input in.las --output out.las --clip 63025000 483450000 63050000 483475000
 
 clips points of in.las with x<63025000 or y<483450000 or x>63050000
-or y>483475000 and stores surviving points to out.las. note that
+or y>483475000 and stores surviving points to out.las. Note that
 clip expects the scaled integer values that the points are stored
 with (not the floating point coordinates they represent).
 
 Eliminating specified returns
------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 ::
   
-  $ las2las -i in.las -o out.las -eliminate_return 1
+  $ las2las --input in.las --output out.las --eliminate_return 1
 
 eliminates all points of in.las that are designated first returns by the 
@@ -57 +80 @@
 
 Limiting based on scan angle
-----------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 ::
 
-  $ las2las -i in.las -o out.las -eliminate_scan_angle_above 15
+  $ las2las --input in.las --output out.las --eliminate_scan_angle_above 15
 
 eliminates all points of in.las whose scan angle is above 15 or below -15 
@@ -67 +90 @@
 
 Limiting based on intensity
----------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 ::
 
-  $ las2las -i in.las -o out.las -eliminate_intensity_below 1000 -remove_extra_header
-
+  $ las2las --input in.las --output out.las --eliminate_intensity_below 1000 
+  
 eliminates all points of in.las whose intensity is below 1000 and stores 
-surviving points to out.las. in addition all variable headers and any 
-additional user headers are stripped from the file.
+surviving points to out.las.
 
 Extract last returns
---------------------
+~~~~~~~~~~~~~~~~~~~~
 
 ::
   
-  $ las2las -i in.las -o out.las -last_only
+  $ las2las --input in.las --output out.las --last_only
 
 extracts all last return points from in.las and stores them to out.las.
+
+Throw out invalid data
+~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+  $ las2las --input in.las --output out.las --skip_invalid
+
+removes invalid (according to the ASPRS LAS file format specification) points.  
+This switch should only be required in a few special circumstances.
+
+Eliminate ground points
+~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+  $ las2las --input in.las --output out.las --eliminate_class 2
+
+removes points with that have a classification of 2.  Points with a 
+classification of 2 are conventionally called ground points, but that convention 
+may not be followed for older LAS 1.0 files.
+
+Convert to 1.1
+~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+  $ las2las --input in.las --output out.las --format 1.1
+  
+converts the in.las file to a 1.1-formatted file.  For the most part, this 
+conversion is "in name only."  For example, 
+
+
+ 
 
 Usage
@@ -101 +157 @@
     las2las -i in.las -last_only -eliminate_intensity_below 2000 -olas > out.las
     las2las -h
+
+.. _`LAStools`: http://www.cs.unc.edu/~isenburg/lastools/