Nathaniel:

Nathaniel Iwuchukwu wrote:

Please what's the procedure or commands for extrating road network from a raster map? i think i have been going round the circle with classofocation and rectification of image. i have used this commands
Hope you didn't mean "class-suffocation" ;-)
but i don't get any results:
i.group
i.composite
i.class
i.cluster
r.digit
i.maxlik
i.gensigset
nothing seems to get me the road network result i want.
What kind of raster are we talking about? If this is a scanned topo map, with the roads symbolized by a certain color, then you might be able to get started with a simple r.mapcalc. First identify the exact value of the pixels of the road, then something like:
r.mapcalc road_rast="if( raster_map=<road_pixel_value>, 1, null() )
then do:
r.thin road_rast out=road_rast_thin
r.to.vect road_rast_thin type=line out=road_vect

Note: this won't get you a road "network", just a line vector. Creating a proper network is another process. Note 2: If you're working with an aerial photo, then the above won't do you any good. In that case you will have to try some procedure of image classification. And then you'll have to deal with the problem you mentioned previously of running out of memory... Either more RAM in the computer, or a smaller region, or a larger resolution.
Please i need help and i am running GRASS on Linux Ubuntu.
thanks.

On Mon, Mar 22, 2010 at 11:09 AM, <[email protected] <mailto:[email protected]>> wrote:

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    Today's Topics:

      1. ERROR: G_malloc: unable to allocate 2147483648 bytes      at
         main.c:153 ([email protected] <mailto:[email protected]>)
      2. Re: importing dem files: projection details? (Markus Neteler)
      3. Re: ERROR: G_malloc: unable to allocate 2147483648 bytes  at
         main.c:153 (Hamish)
      4. Re: make command (install add on) (schorschli)
      5. Helpp needed to call Grass from inside Python Plugin
         (Bishwarup Banerjee)
      6. grass editing (Gary Nobles)
      7. Re: ERROR: G_malloc: unable to allocate 2147483648 bytes  at
         main.c:153 (Glynn Clements)
      8. Osgeo4W grass error (Pablo Carreira)


    ----------------------------------------------------------------------

    Message: 1
    Date: Sun, 21 Mar 2010 13:02:00 -0700
    From: [email protected] <mailto:[email protected]>
    Subject: [GRASS-user] ERROR: G_malloc: unable to allocate 2147483648
           bytes   at main.c:153
    To: [email protected] <mailto:[email protected]>
    Message-ID:
           <[email protected]
    <mailto:[email protected]>>
    Content-Type: text/plain; charset=us-ascii

    Hi, i am trying extract road network from a raster map but each
    time i run the image filter, i get this error message: ERROR:
    G_malloc: unable to allocate 2147483648 bytes at main.c:153.

    i also connnot use the i.class command on my windows machine which
    is the platform i am working with. please how can i extract a road
    network from raster map on windows platform?
    thank you.
    Nathaniel


    ------------------------------

    Message: 2
    Date: Mon, 22 Mar 2010 00:23:48 +0100
    From: Markus Neteler <[email protected] <mailto:[email protected]>>
    Subject: Re: [GRASS-user] importing dem files: projection details?
    To: Tyler Smith <[email protected] <mailto:[email protected]>>
    Cc: GRASS user list <[email protected]
    <mailto:[email protected]>>
    Message-ID:
           <[email protected]
    <mailto:[email protected]>>
    Content-Type: text/plain; charset=ISO-8859-1

    On Mon, Mar 15, 2010 at 7:38 PM, Tyler Smith <[email protected]
    <mailto:[email protected]>> wrote:
    > On 03/15/2010 09:38 AM, Markus Neteler wrote:
    >> On Mon, Mar 15, 2010 at 1:35 PM, Tyler
    Smith<[email protected] <mailto:[email protected]>>  wrote:
    >>> On 03/15/2010 03:42 AM, Markus Neteler wrote:
    >>>
    >>> Trying the auto route:
    >>>
    >>> grass64 -gui
    >>> select define new location with georeferenced file
    >>> select the dem file: k42.dem
    >>> select the TN transformation, as probably better than the
    default for
    >>> adjacent Kentucky
    >>> enter GRASS with the newly created location and the PERMANENT
    mapset
    >>>
    >>> Results in this error:
    >>>
    >>> "g.proj or projection error: ERROR: default region is invalid
    >>>    line 3:<north: 1080:43:46N>"
    >>>
    >>> So GRASS has automatically set up the location using degrees,
    and then
    >>> get
    >>> confused when the raster co-ordinates are provided in meters.
    Which
    >>> appears
    >>> to be fairly close to the sort of problem I ran into when
    setting this up
    >>> manually. What am I missing?
    >>>
    >>
    >> Please post the output of gdalinfo on that file. GRASS uses
    GDAL to detect
    >> projections from metadata.
    >>
    >> Markus
    >>
    >
    > Thanks for help! Here it is:
    >
    > gdalinfo k42.dem
    > Driver: USGSDEM/USGS Optional ASCII DEM (and CDED)
    > Files: k42.dem
    > Size is 1222, 1535
    > Coordinate System is:
    > GEOGCS["NAD83",
    >    DATUM["North_American_Datum_1983",
    >        SPHEROID["GRS 1980",6378137,298.257222101,
    ...
    > Metadata:
    >  AREA_OR_POINT=Point
    > Corner Coordinates:
    >
    > Upper Left  (    1467.054,    1080.729)
    > Lower Left  (    1467.054,    1067.938)
    > Upper Right (    1477.237,    1080.729)
    > Lower Right (    1477.237,    1067.938)
    > Center      (    1472.146,    1074.334)
    ...

    I get actually a somewhat different result (GDAL trunk):

    gdalinfo m40.dem
    Driver: USGSDEM/USGS Optional ASCII DEM (and CDED)
    Files: m40.dem
    ...
    Corner Coordinates:
    Upper Left  (    1447.317,    1055.177) (Invalid angle,Invalid angle)
    Lower Left  (    1447.317,    1042.411) (Invalid angle,Invalid angle)
    Upper Right (    1457.509,    1055.177) (Invalid angle,Invalid angle)
    Lower Right (    1457.509,    1042.411) (Invalid angle,Invalid angle)
    Center      (    1452.413,    1048.794) (Invalid angle,Invalid angle)
    Band 1 Block=1223x1532 Type=Float32, ColorInterp=Undefined
     NoData Value=-32767
     Unit Type: ft

    You may want to signal this as GDAL bug in the GDAL butracker:
    http://trac.osgeo.org/gdal/

    Unless GDAL doesn't read it correctly, it won't be understood by
    GRASS.
    I tested with
    ftp://ftp.kymartian.ky.gov/dems_usgs/m39.dem.zip

    Markus


    ------------------------------

    Message: 3
    Date: Sun, 21 Mar 2010 22:41:12 -0700 (PDT)
    From: Hamish <[email protected] <mailto:[email protected]>>
    Subject: Re: [GRASS-user] ERROR: G_malloc: unable to allocate
           2147483648 bytes        at main.c:153
    To: [email protected]
    <mailto:[email protected]>, [email protected]
    <mailto:[email protected]>
    Message-ID: <[email protected]
    <mailto:[email protected]>>
    Content-Type: text/plain; charset=us-ascii

    Nathaniel wrote:
    > Hi, i am trying extract road network
    > from a raster map but each time i run the image filter, i
    > get this error message: ERROR: G_malloc: unable to allocate
    > 2147483648 bytes at main.c:153.

    aka it is trying to use >2gig RAM and there is not enough memory.
    Possibly because you are not using a 64bit OS, and possibly because
    you don't actually have that much memory in your computer.
    Maybe try on a smaller dataset?

    > i also connnot use the i.class command on my windows
    > machine which is the platform i am working with.

    you will have to wait for someone to build GRASS 6.4.0RC6 for Cygwin.
    i.class uses UNIX-style Xmonitors which are not available on standard
    MS Windows. (or try GRASS on a Mac or Linux computer/virtual machine)


    Hamish






    ------------------------------

    Message: 4
    Date: Mon, 22 Mar 2010 01:44:01 -0800 (PST)
    From: schorschli <[email protected]
    <mailto:[email protected]>>
    Subject: [GRASS-user] Re: make command (install add on)
    To: [email protected] <mailto:[email protected]>
    Message-ID: <[email protected]
    <mailto:[email protected]>>
    Content-Type: text/plain; charset=us-ascii


    Thanks for answering.


    >Are you sure about this directory?

    >MODULE_TOPDIR should point to the GRASS installation directory which
    >contains bin/, lib/ and other GRASS stuff.


    Yes, the directory is the one containing the grass-folders (bin/,
    lib/ and
    others).

    I could solve this problem. It was not a wrong MODULE_TOPDIR path,
    but wrong
    extensions for the makefiles.



    Now I can run the make command. But this is resulting in hunderts
    of errors
    and warning. Here is a printscreen of the first couple of lignes
    in the
    console...

    http://n2.nabble.com/file/n4776893/errors.png
    http://n2.nabble.com/file/n4776893/errors.png errors.png


    So maybe its better to just give it up with the addons...



    --
    View this message in context:
    http://n2.nabble.com/make-command-install-add-on-tp4764072p4776893.html
    Sent from the Grass - Users mailing list archive at Nabble.com.


    ------------------------------

    Message: 5
    Date: Mon, 22 Mar 2010 17:58:42 +0530
    From: Bishwarup Banerjee <[email protected]
    <mailto:[email protected]>>
    Subject: [GRASS-user] Helpp needed to call Grass from inside Python
           Plugin
    To: GRASS developers list <[email protected]
    <mailto:[email protected]>>,
           [email protected] <mailto:[email protected]>
    Message-ID:
<[email protected]
    <mailto:[email protected]>>
    Content-Type: text/plain; charset="iso-8859-1"

    Hi All,

    I want to call the grass functionalities from inside my python
    plugins, in
    QGIS
    For example: the Grass's raster to polygon script, with out going
    inside the
    grass plugin.
    Can I set the Grass Mapset, and location from inside my python plugin?
    Is this possible?
    my configurations are:
    QGIS 0.11, GRASS 6.3, python 2.5, Windows

    Thank you in advance
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    Message: 6
    Date: Mon, 22 Mar 2010 03:10:42 -0800 (PST)
    From: Gary Nobles <[email protected] <mailto:[email protected]>>
    Subject: [GRASS-user] grass editing
    To: [email protected] <mailto:[email protected]>
    Message-ID: <[email protected]
    <mailto:[email protected]>>
    Content-Type: text/plain; charset=us-ascii


    Hi, I have been editing a grass point dataset in qgis
    unfortunately I have
    just added 400 centroids rather than points! Is there anyway to
    delete just
    the centroids?

    Thanks

    Gary
    --
    View this message in context:
    http://n2.nabble.com/grass-editing-tp4777030p4777030.html
    Sent from the Grass - Users mailing list archive at Nabble.com.


    ------------------------------

    Message: 7
    Date: Mon, 22 Mar 2010 13:54:49 +0000
    From: Glynn Clements <[email protected]
    <mailto:[email protected]>>
    Subject: Re: [GRASS-user] ERROR: G_malloc: unable to allocate
           2147483648 bytes        at main.c:153
    To: Hamish <[email protected] <mailto:[email protected]>>
    Cc: [email protected]
    <mailto:[email protected]>, [email protected]
    <mailto:[email protected]>
    Message-ID: <[email protected]
    <mailto:[email protected]>>
    Content-Type: text/plain; charset=us-ascii


    Hamish wrote:

    > > Hi, i am trying extract road network
    > > from a raster map but each time i run the image filter, i
    > > get this error message: ERROR: G_malloc: unable to allocate
    > > 2147483648 bytes at main.c:153.
    >
    > aka it is trying to use >2gig RAM and there is not enough memory.
    > Possibly because you are not using a 64bit OS, and possibly because
    > you don't actually have that much memory in your computer.
    > Maybe try on a smaller dataset?

    2147483648 is exactly 2GiB; I'm wondering if that's the actual size
    (e.g. 16384 x 16384 x 8bytes/cell) or an uninitialised variable (e.g.
    initialised to INT_MIN in the code and not updated).

    On Linux, it is possible to allocate 2GiB on a 32-bit system, provided
    that there's a contiguous block (in practice, this means that the
    stack size isn't "unlimited"). You don't need that much physical RAM,
    only swap (although performance may be unacceptable if you're relying
    upon swap; it depends upon the access pattern).

    "Desktop" versions of Windows normally only allow 2GiB on 32-bit
    systems. Server versions allow up to 3GiB, and the desktop versions
    can be tweaked to allow it (but it isn't straightforward).

    > > i also connnot use the i.class command on my windows
    > > machine which is the platform i am working with.
    >
    > you will have to wait for someone to build GRASS 6.4.0RC6 for
    Cygwin.
    > i.class uses UNIX-style Xmonitors which are not available on
    standard
    > MS Windows. (or try GRASS on a Mac or Linux computer/virtual
    machine)

    I'll probably be building RC6 for Cygwin some time today.

    --
    Glynn Clements <[email protected]
    <mailto:[email protected]>>


    ------------------------------

    Message: 8
    Date: Mon, 22 Mar 2010 12:03:01 -0300
    From: Pablo Carreira <[email protected]
    <mailto:[email protected]>>
    Subject: [GRASS-user] Osgeo4W grass error
    To: <[email protected] <mailto:[email protected]>>
    Message-ID: <[email protected]>
    Content-Type: text/plain; charset="utf-8"


    Hi, I'am trying to start the latest osgeo4w grass on windows 7 but
    I get an error when I select the dataset. Is it about the
    language? How can I start grass in english and not in portuguese?

    Regards,
    Pablo.


    Here is the error:


    C:\>"C:\OSGeo4W\apps\grass\grass-6.4.0svn"\etc\init.bat -wxpython
    access: Invalid argument
    ERRO:LOCAÃ├O << C:\teste/<UNKNOWN> >> indisponà vel
    Traceback (most recent call last):
     File
    "C:/OSGeo4W/apps/grass/grass-6.4.0svn/etc/wxpython/gis_set.py",
    line 853,
     in <module>
       GRASSStartUp = StartUp(0)
     File
    "C:\OSGeo4W\apps\Python25\lib\site-packages\wx-2.8-msw-unicode\wx\_core.p
    y", line 7935, in __init__
       self._BootstrapApp()
     File
    "C:\OSGeo4W\apps\Python25\lib\site-packages\wx-2.8-msw-unicode\wx\_core.p
    y", line 7509, in _BootstrapApp
       return _core_.PyApp__BootstrapApp(*args, **kwargs)
     File
    "C:/OSGeo4W/apps/grass/grass-6.4.0svn/etc/wxpython/gis_set.py",
    line 824,
     in OnInit
       StartUp = GRASSStartup()
     File
    "C:/OSGeo4W/apps/grass/grass-6.4.0svn/etc/wxpython/gis_set.py",
    line 165,
     in __init__
       self._set_properties()
     File
    "C:/OSGeo4W/apps/grass/grass-6.4.0svn/etc/wxpython/gis_set.py",
    line 206,
     in _set_properties
       self.OnSetDatabase(None)
     File
    "C:/OSGeo4W/apps/grass/grass-6.4.0svn/etc/wxpython/gis_set.py",
    line 664,
     in OnSetDatabase
       self.OnSelectLocation(None)
     File
    "C:/OSGeo4W/apps/grass/grass-6.4.0svn/etc/wxpython/gis_set.py",
    line 616,
     in OnSelectLocation
       self.listOfLocations[self.lblocations.GetSelection()]))
     File
    "C:/OSGeo4W/apps/grass/grass-6.4.0svn/etc/wxpython/gis_set.py",
    line 584,
     in UpdateMapsets
       stderr=None)
     File
    "C:\OSGeo4W\apps\grass\grass-6.4.0svn\etc\wxpython\gui_modules\gcmd.py",
    line 356, in __init__
       _("Error: ") + self.GetError()))
     File
    "C:\OSGeo4W\apps\grass\grass-6.4.0svn\etc\wxpython\gui_modules\gcmd.py",
    line 449, in GetError
       return unicode(msg, "utf-8")
    UnicodeDecodeError: 'utf8' codec can't decode bytes in position
    4-5: invalid dat
    a










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