In what formats is the PSLC
LiDAR data available?
ArcInfo Interchange Files (.e00)
ArcInfo
interchange files have an .e00 extension and are commonly know as e00
files.
The .e00 file format
is verbose ASCII, expanding gridded DEMs to approximately 4 times their
binary
size, but is easily imported into an ESRI Grid for use in Arc-Info,
ArcView and ArcGIS.
It also carries
projection information.
These are
available online for the bare
earth and also the top surface.
GeoTIFF
Hillshade TIFF images with world
files (.tif and .tfw).
These are simple
image files that show the shaded relief derived from DEMs by
considering the illumination angle of the sun and shadows. These
files do
not have elevation information.
These are
available online for the bare
earth and also the top surface.
ASCII
PSLC Lidar data is also available
in ASCII format.
We have the bare earth
ASCII and the all-returns ASCII.
The
bare earth ASCII files are
composed of the returns classified as ground.
These
files are simple text files where each line (row) has
values for
easting, northing and elevation.
Each quarter
quad is broken down
into 1/25
th tiles
The
all-returns ASCII files
have all recorded returns during each survey mission.
These
have returns for buildings, vegetation, etc.
They
are simple text files where
each line (row) has values for easting, northing and elevation, but
they
also have
other attributes such as the return number, a time stamp, scan angle,
some have intensity and classification code.
The
attributes vary a little between
projects done in different years.
Reference
the
metadata for the header information.
These files also tend to be very large in
size.
Each quarter
quad is broken down
into 1/25
th tiles to make them
more user friendly. (There is an execption for a couple of
datasets, see
tile scheme)
Both of these datasets are
available online. You can also see "
How can I get
ASCII data?".
LAS
Projects from 2006 and beyond also have .LAS files.
LAS format is an open format that allows most software packages to
utilize the data. This files contain a record for each
return. The current version being used is LAS format version
1.1. These files are only available via special request.
Use the same system in "
How
can I get
ASCII data?".
If you have
ArcGIS 8.x or
ArcGIS
9.x with the ArcInfo License, then you can use the “Import From
Interchange
File” tool in the toolbox.
This tool is
located in a different location for each version of ArcGIS.
The easiest way to find it is to do a search.
Once you have it open, make
sure you specify “Grid” for feature type. You can also use the
Import command
in ArcInfo Workstation.
If you have ArcGIS 8.x or ArcGIS 9.x
with the ArcView license, you can
import the .e00 file by using the “Import from Interchange file” tool
under
Conversion tools in ArcCatalog. This
tool does have a glitch. It creates a
.aux file that does not allow ArcMap or ArcCatalog to recognize the
files and
you get an “Invalid raster dataset” error message.
You will need to delete the .aux file by following the
directions in the related ESRI
Technical Article (Article ID number 21443 in
support.esri.com
).
Alternatively you can download
Import71 to import your files.
You can
download it free of charge from geocomm.com.
(
http://software.geocomm.com/translators/arcview/)
This should not give you any problems.
In ArcView 3.2 you can use
Import71 to translate the .e00 files into ESRI Grid files.
Import 71 should be in you “ArcView GIS 3.2”
directory. Import71 is automatically installed when ArdView
3.2 is installed, there is no need to downloaded it.
In
AutoCAD
you will need to use the bare earth ASCII files.
AutoCAD
does not have a translator for raster .e00 files.
See
“How can I get ASCII data?".
For all other software check your user's manual for formats
supported.
If it's not supported, you may be able to find a translator for your
software. Your software's technical support may also be helpful.
Is there
metadata?
Yes, see our
metadata page for data through 2005.
The rasters for 2006 and beyond have internal metadata.
Projects from 2005 and beyond also have
project
reports available.
PSLC
LiDAR data is broken down into USGS quarter quads.
ASCII data is further broken down into 25 tiles per quarter quad.
Each quarter quadrangle is subdivided into a 5 x 5 array of tiles
organized from upper-left to lower-right as follows:
01 02 03 04 05
06 07 08 09 10
11 12 13 14 15
16 17 18 19 20
21 22 23 24 25
The two-digit tile number is appended to the end of the file name.
There are two exceptions. One where the tile scheme is 1/64th of
a quad.
The projects affected are the Lewis County project in 2006 and
the Eastern WA\OR River corridors flown in 2007. The other
exception is the Sumpter Oregon project. This project has it's
own unique tiling scheme.
See
index files in for further reference
for both tile schemes.
What is the header for the ASCII data?
Project from 2000 to 2005
For the bare earth ASCII data it
will always be X, Y, Z (Easting, Northing and elevation).
The All returns ASCII data varies depending on the project year.
It is best to
reference the
metadata for the appropriate
header information. Data from 2006 and beyond has a header in
each ASCII file.
Projects from 2006 and beyond
The ASCII files for these projects come with headers included in each
file. You may also take a look a the
project reports.
The best source for projection
information for project between 2000 and 2004 is the
metadata. Grid data for projects from
2005 and beyond have metadata or projection files attached. These
also have
project reports
available.
In general all PSLC LiDAR data is
collected during
the winter/leaf-off season from December to Early April.
For projects flown between 2000 and 2004 reference the
metadata for a range of dates. For
exact days you may use the
flight line
trajectory
files when available. Otherwise, you may need to
access
the All-returns ASCII data. When using the all-returns ASCII
data you will need to
look at the time stamp on each return.
For projects flown in 2005 and foward you may reference the
Project Reports for a range of
dates. For exact days you should use the
flight line trajectory
files. If you choose to, you can also use the all-returns
ASCII data, but be warned that it will be a time consuming project.
In the PSLC LiDAR data up to four
returns can be recorded
per laser pulse. Number_of_returns is the total returns for a
pulse (up to a maximum of
4).
Return_number is assigned as a number from 1 to 7 in a scheme that
identifies
which return is the last return recorded for a pulse. See below
for a description of this scheme. Also see the
metadata for more information on other
attribute information in the all-return ASCII data.
1 first return with subsequent returns detected
2 second return with subsequent returns detected
3 third return with subsequent returns detected
4 fourth return
5 first return with no subsequent returns detected
6 second return with no subsequent returns detected
7 third return with no subsequent returns detected
How can I get ASCII data?
The bare earth ASCII data and the
All-returns ASCII data are
available online.
Large quanties of data are also available via special request, but it
does take much more time and the requester will need to provide a USB
external hard drive as well as postage to return the drive.
Include a list of USGS
quarter
quad numbers with the request.
Use
the
index shapefiles to see which quads
you need. You can submit a request to Diana Martinez at
dmartinez@psrc.org
or at (206) 971-3052.
I forgot my password, how do I get it
emailed to me
again?
I have my password but I can’t get
into the download site.
See the
LiDAR
Access page for a step-by-step guide to the download site.
Also keep in mind that the login and the password
are case sensitive. Make sure you enter your login (which is your
email
address) correctly.
Another
common problem is misspelling your email
address when you initially registered. If you
continue to have problems email
Diana Martinez at
dmartinez@psrc.org
or Harvey Greenberg at
hgreen@u.washington.edu.