GRASS FAQ: Difference between revisions

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# I can't find pq.dll: try copy cygpq.dll to pq.dll
# I can't find pq.dll: try copy cygpq.dll to pq.dll


=Errors=
= Errors =
# In a Latitude-Longitude location I'm getting the error ''Illegal latitude for North'' when importing an unprojected raster image: Unprojected images are given a resolution of 1 pixel per line, and so any image with a height of more than 90 pixels will try and write data to an impossible latitude. <br> '''Solution''': import the image into a simple XY location and georeference the image with either r.region (if bounds are simple and known) or i.points and i.rectify. An automated alternative to r.region is to create a "World File" to be used by r.in.gdal. See the GeoTIFF format help page at [[http://www.gdal.org]].
 
* In a Latitude-Longitude location I'm getting the error ''Illegal latitude for North'' when importing an unprojected raster image: Unprojected images are given a resolution of 1 pixel per line, and so any image with a height of more than 90 pixels will try and write data to an impossible latitude. <br> '''Solution''': import the image into a simple XY location and georeference the image with either r.region (if bounds are simple and known) or i.points and i.rectify. An automated alternative to r.region is to create a "World File" to be used by r.in.gdal. See the GeoTIFF format help page at http://www.gdal.org.
: In GRASS 6.5 and 7, {{cmd|r.in.gdal|version=65}} has a new ''-l'' flag to constrain the import to valid lat/lon ranges. Another good alternative is to use <tt>gdal_translate -a_ullr</tt> to convert the dataset into a GeoTiff with reset bounds. See the [[MODIS#Import|MODIS]] wiki page for details.
: Use <tt>gdalinfo</tt> to test your data set. What it sees, r.in.gdal will see.
 


[[Category:FAQ]]
[[Category:FAQ]]

Revision as of 14:20, 12 September 2009

This pages contains a growing list of Frequently Asked Questions (FAQs). Feel free to add text, "Edit" button for that. See also Category: FAQ for more articles.

Usage

  1. In a site map, how to select all the points that are at the edge? - Points Edge Selection
  2. How to create a buffer around polygons using v.buffer? - Vector Buffer
  3. What are LOCATIONs and MAPSETs? - Location and Mapsets
  4. Starting GRASS - Starting GRASS
  5. ERROR: Default region not set - Error Region
  6. Nothing shows in monitor window - Region Map
  7. How to show labels, such as street labels on a vector map? - Labels Show
  8. What is a raster MASK? - GRASS Raster Mask
  9. What is an attribute? - GRASS Attributes
  10. Is is possible to switch from one LOCATION to another while running GRASS? - Switch Locations
  11. Changing region during operation? - Changing Region
  12. Point in polygon test: - Point in Polygon
  13. Georeferencing an image?
  14. How do I reproject a raster or vector map? - Map Reprojection
  15. How do I enjoy high quality statistic analysis in GRASS? GRASS and Rstat
  16. What is the difference between pseudo-topological and real topological vect formats? - Topo Issue
  17. How to to aggregate values from one polygon layer to another ? - Aggregate Values
  18. How to diplay a vector (polygon) map colored by the attributes in a particular column? Vector Attribute Display
  19. How to Convert vector types
  20. How to Dissolve polygons

Data

  1. Can I map data from an arbitrary database model to work with GRASS without having to restructure or create a new database?
  2. How can I drop columns in a sqlite-database? - Sqlite Drop Column
  3. How to unlock SQLite database? - SQLite unlock database

Technical

  1. GRASS 6 symbols - [README]
  2. GRASS 5.7 vector architecture - Vector Faq GRASS57
  3. Does GRASS57 installation override my stable GRASS5x installation? GRASS5x and 57
  4. Are GRASS 5.0.x/5.3.x/5.4.x raster maps compatible with GRASS57? Yes!
  5. How do I compile/install GRASS57? Compile and Install

Installation

GRASS 6 compilation problems

  1. Can't find a library even after I've built and installed it: Make sure that /usr/local/lib (or where you installed it) is listed in your /etc/ld.so.conf file and (as root) run /sbin/ldconfig.
  2. grass 5.7 compilation problems: - GRASS57 Compilation
  3. grass 5.3, 5.4 compilation problems: - GRASS53 Compilation
  4. How do I install grass in windows 2000: - WinGRASS Installation

GRASS and Cygwin

  1. How do I find the Cygwin packages to install? - Cygwin Packages
  2. I can't find pq.dll: Make sure you installed the PostgreSQL package in the Cygwin [installer].
  3. I can't find pq.dll: try copy cygpq.dll to pq.dll

Errors

  • In a Latitude-Longitude location I'm getting the error Illegal latitude for North when importing an unprojected raster image: Unprojected images are given a resolution of 1 pixel per line, and so any image with a height of more than 90 pixels will try and write data to an impossible latitude.
    Solution: import the image into a simple XY location and georeference the image with either r.region (if bounds are simple and known) or i.points and i.rectify. An automated alternative to r.region is to create a "World File" to be used by r.in.gdal. See the GeoTIFF format help page at http://www.gdal.org.
In GRASS 6.5 and 7, r.in.gdal has a new -l flag to constrain the import to valid lat/lon ranges. Another good alternative is to use gdal_translate -a_ullr to convert the dataset into a GeoTiff with reset bounds. See the MODIS wiki page for details.
Use gdalinfo to test your data set. What it sees, r.in.gdal will see.
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