On 03/07/2011 08:27 PM, Michael P. Gerlek wrote:
I'm not keen on more file formats in the world, but one thing I've on my
wish list is a sort of "binary" version of the ascii format to use for
interchange -- that is, a text header file which lists the columns and data
types for a point (e.g. as a C-style struct), and a binary file which just
stores the binary points, e.g. as an array of structs. Trivial to read and
write, arbitrarily flexible, and smaller than ascii. And, perhaps,
compressible with laszip technology.
We did something quite similar for the SAGA GIS native point cloud
format .spc. It's more a less a binary table with at least x,y,z and any
other (numeric) attribute you like to store. At the moment we don't use
a text header, column headings and data type are stored within the binary.
Would be nice to have libPC support the SAGA format, like GDAL does for
SAGA grids. Is there some tutorial on how to write libPC "drivers"?
Volker
-mpg
-----Original Message-----
From: [email protected] [mailto:liblas-devel-
[email protected]] On Behalf Of Martin Isenburg
Sent: Sunday, March 06, 2011 6:53 AM
To: Ben Discoe
Cc: liblas-devel
Subject: Re: [Liblas-devel] Header::SetDataFormatId, and supported
schemas
hi ben.
ePointFormat0: has dimensions "X, Y, Z, Intensity, Return Number,
Number of Returns, Scan Direction, Flightline Edge, Classification,
Scan Angle Rank, User Data, Point Source ID".
ePointFormat1: all of those, plus it adds "Time".
ePointFormat2: adds Color ("Red", "Green", "Blue")
ePointFormat3: adds "Time" and Color.
ePointFormat4: adds "Time" (and WavePacket?)
ePointFormat5: adds ???
ePointFormat5: adds "Time" and Color and WavePacket
Besides clarifying those options a bit more for the documentation,
could someone tell if this means we cannot define our own schema?
We cannot. LAS has those 6 point types. If you only use XYZ and RGB then
you should use point type 2. If you are worried about space (e.g.
storing too many unused fields) you can consider leaving all those fields
at
zero and storing your data LASzip compressed ... they will be pretty much
"compressed away" completely.
Martin
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