LandSerf uses its own platform independent compressed file format for storing surface models. Opening
and saving of files in this format is achieved via the File->Open
and File->Save
menu items or the and
buttons respectively. When saving
a file to disk, it is the primary raster map or selected vector map that is output.
Import and export of files to and from LandSerf can be in a range of formats. See file formats used by LandSerf for more details.You may also wish to view some guidelines on importing elevation models to help with this process.
The file format for both importing and exporting data is selected from the File dialogue in the Files of type:
drop-down menu. When typing the name of a file to save, the name with file extension should be typed (e.g.
dem.srf
, rivers.vec
etc.). In some cases, the type of file extension will determine
the precise format of the output file (e.g. image files can have the extension .jpg
, .gif
or .png
; VRML files can will be uncompressed if given the extenions .wrl
or .vrml
,
but compressed if given the extenison .wrz
).
Any number of raster or vector maps may be imported into LandSerf, limited only by the memory capacity of the machine running the software. Maps for processing or display can be selected by clicking on the relevant thumbnail image on the left-hand side of the LandSerf window.
LandSerf can import and export rasters as ArcGIS ASCII or binary (BIL) files. Even if you do not have access to ArcGIS or ArcView, you may find these facilities useful for sharing data. ArcGIS vector files can also be imported as shapefiles or ASCII 'generate' vector coverages, and exported as as ASCII 'generate' vectors and attribute tables.
If you have access to the GIS GRASS, both rasters and vectors may be exported using the GRASS modules
r.out.ascii
and v.out.ascii
. These files may be read directly into LandSerf.
Note that to import vector attributes as well as geometry, you will need the relevant file from GRASS'
dig_att
file in addition to the output produced by v.out.ascii
.
If you have access to the landscape visualisation software
Terragen or VistaPro or the you can import and export rasters directly to and from LandSerf. To export
from VistaPro, choose the finest polygon resolution (1), and select Save ASCII Z
from the
Save
menu. To export or import files to or from Terragen, rasters are scaled to 257x257 pixels
planimetricly and 256 (8 bits) integers in elevation. Be aware that this can degrade the quality of the
transferred DEM.
Ordnance Survey Raster DEMs at both 10m ('Profile data) and 50m ('Panorama' data)resolutions may be read
using the Ordnance Survey NTF raster DEM
format. Ordnance Survey vector data (e.g. LandLine,
Strategi, Meridian and MasterMap) can also be imported using either the Ordnance Survey NTF vector
file
or Ordnance Survey MasterMap
formats. On import of vector data with multiple
attributes, you are presented with the option of importing only a subset of these attributes (see figure
below). Once imported, data are stored in LandSerf's own attribute table that may be edited later.
Most elevation data from the US Geological Survey (USGS) are now distributed in one of the ArcGIS raster
formats. However, some are still distributed in 'Native DEM' format. These data can be imported directly
by selecting the USGS Native DEM
format.
Image data such as areal photos, rasterized scanned maps and remotely sensed images can be imported
directly using the image
format selector. Formats available for import include GIF, JPEG,
PNG and uncompressed TIFF. Currently, GeoTIFF format is not supported. However georeferencing information
may be stored in a 'world' file sharing the same name as the image, but with a modified extension name as
indicated below:
Image name | World file name |
photo.tif | photo.tfw |
map.gif | map.gfw |
landcover.jpg | landcover.jgw |
band7.png | band7.pgw |
To import other raster text files, use the Generic text raster
format option. Files in this
format consist of text of nrows rows running North to South, with each row consisting of ncols
columns of whitespace separated z-values. These numbers may be integer or real. There should be no header
information associated with the file, although lines starting with a #
symbol may be used as
comments and are ignored. Note that to import ASCII data that run row-wise from South to North use the
VistaPro raster
format instead. To import text rasters stored column-wise from South to North,
select the EDX
format.
If you wish to share data with software (or data) that use (x,y,z) coordinate triplets to locate elevation
values (e.g. a spreadsheet), you can use the import/export Generic Point File
formats. Export
converts the primary raster values into a set of (x,y,z) triplets with the option of sampling points
randomly or systematically before output.
VRML world
format will export the primary raster surface and create a simple VRML world in
which to display it. The image above shows such a file viewed by the Cortona VRML browser. Note that
to store the VRML file in compressed format, the file extension .wrz
should be used. If you
do not wish to compress the file (some older VRML viewers cannot process compressed files), choose either
.wrl
or .vrml
as a file extension.
LandSerf will also import the binary 'BT' raster format used by the Virtual Terrain Project. Again, even if you do not use any of the VTP software directly, this can be a useful DEM interchange format for exchanging data.
The display shown in LandSerf's main window can be saved as a GIF, PNG or JPEG graphics file by selecting
the Image
format from the save dialogue. The dimensions of the image will be set to the size
of the graphics window at the time the image is saved.
Vector data may be exported in SVG format for sharing on the Web. For browsers with a suitable SVG
plug-in, web-based maps may be created that allow users to zoom and pan while maintaining high quality
output. This is also useful for producing high quality printed output. Data may be compressed depending
on whether a .svgz
(compressed) or .svg
(uncompressed) extension is supplied.
Print Preview
from the
File
menu. Printer output can be selected from the same menu or the
button.