That image is still saved in a color image format (RGB).  I don't know what
editing application you're using, but in GIMP for example, you can change it
with Image->Mode->Grayscale.  Photoshop has a similar option.

Josh

On Thu, May 6, 2010 at 9:04 AM, pratyush jalan <pratyush.jalan@gmail.com>wrote:

> Hi John,
>
> I am using the grayscale image but I am still having problems with that.
> Here is the console error output -:
> OGRE EXCEPTION(2: InvalidParameterException): ERROR: Image is not a
> grayscale image. in HeightmapTerrainPageSource::requestPage at
> OgreHeightmapTerrainPageSource.cpp (line: 210)
> ...
>
> I have also attached my grayscale image
>
> Thanks.
>
>
> On Wed, May 5, 2010 at 10:34 PM, John Hsu <johnhsu@willowgarage.com>wrote:
>
>> Hi Pratyush,
>> Please post the console error outputs and attach track.jpg.  But I suspect
>> you need to convert track.jpg to grayscale (single channel).
>> John
>>
>>
>> On Wed, May 5, 2010 at 6:28 PM, pratyush jalan <pratyush.jalan@gmail.com>wrote:
>>
>>> Hi John
>>>
>>> So I was using Heightmap because one of one of friend had once created
>>> his world file (similar to the empty_world file) and this is what he had -:
>>> <model:physical name="terrain_model">
>>>  <xyz>0.0 0.0 -10</xyz>
>>>     <body:heightmap name ="terrain_body">
>>>       <geom:heightmap name="terrain_geom">
>>>  <image>track.jpg</image>
>>>         <worldTexture>track.jpg</worldTexture>
>>> <size>13 13 0.05</size>
>>>       </geom:heightmap>
>>>     </body:heightmap>
>>>   </model:physical>
>>> This was giving me the problem of " Image is not grayscale ". I changed
>>> that to one as used in the empty_world file
>>>  <model:physical name="willow_map">
>>>    <xyz>0 0 0</xyz>
>>>    <rpy>180 0 0</rpy>
>>>    <static>true</static>
>>>    <body:map name="willow_map_body">
>>>      <geom:map name="willow_map_geom">
>>>        <image>*track.jpg*</image>
>>>        <threshold>1</threshold>
>>>        <granularity>1</granularity>
>>>        <negative>false</negative>
>>>        <scale>0.01</scale>
>>>        <offset>0 0 0</offset>
>>>        <material>Gazebo/Rocky</material>
>>>      </geom:map>
>>>    </body:map>
>>>   </model:physical>
>>>
>>> But when I launch this, its gives me an error Coordinate out of range. It
>>> keeps displaying this error. ( in the first code, I changed the heightmap to
>>> just map and I am getting same as this error) I am sorry but I couldn't find
>>> any documentation for the world file.
>>>
>>> Thanks.
>>>
>>> Pratyush Jalan
>>>
>>>
>>>
>>> On Tue, May 4, 2010 at 11:21 PM, John Hsu <johnhsu@willowgarage.com>wrote:
>>>
>>>>
>>>> On Tue, May 4, 2010 at 7:50 PM, pratyush jalan <
>>>> pratyush.jalan@gmail.com> wrote:
>>>>
>>>>> Hi John
>>>>>
>>>>> Thanks for the quick reply.
>>>>>
>>>>> 1) Yes, I am using heightmap. What should I use to use color image for
>>>>> the world ?
>>>>>
>>>>
>>>> I am not sure what you are trying to do here.  HeightMap takes a single
>>>> channel image and use that information to create a contoured trimesh floor
>>>> based on the value of the image intensity.  Are you trying to texture the
>>>> world with a color image?  If that's the case, heightmap will not do the
>>>> right thing here.
>>>>
>>>>
>>>>>
>>>>> 2) No I did not hit Ctrl+C. For running the pr2 robot, I first run the
>>>>> roslaunch gazebo_worlds empty_world.launch  then on another terminal
>>>>> roslaunch pr2_gazebo pr2.launch
>>>>> then on another terminal I run my C++ controller code( which basically
>>>>> sends velocity commands by publishing to the specific topic).
>>>>> This works great.
>>>>>
>>>>> But for the simplecar.model when I launch...it gives the specific
>>>>> message I sent in the earlier email and then by itself it return to the
>>>>> command prompt ( this does not happen when running pr2). heres the following
>>>>> content of my simplecar.launch
>>>>>
>>>>> <launch>
>>>>> <param name="simplecar" textfile="$(find
>>>>> gazebo_worlds)/objects/simplecar.model" />
>>>>>
>>>>>   <!-- push urdf to factory and spawn robot in gazebo -->
>>>>>   <node name="spawn_simplecar" pkg="gazebo_tools" type="gazebo_model"
>>>>> args="-p simplecar -x -5.5 -y -3.5 -z 1  -R 0 -P 0 -Y 0 spawn simplecar"
>>>>> respawn="false" output="screen" />
>>>>> </launch>
>>>>>
>>>>
>>>> Judging from above launch script, it's likely you have not spawned a
>>>> controller?  Please take a look at the example in
>>>> pr2_examples_gazebo/single_link.launch.  This example starts up a single
>>>> actuated joint using SimpleTransmission and JointPositionController.  You
>>>> might want to use JointEffortController or JointVelocityController for your
>>>> particular use case.
>>>>
>>>> John
>>>>
>>>>
>>>>> Thanks.
>>>>>
>>>>> Pratyush
>>>>>
>>>>>
>>>>> On Tue, May 4, 2010 at 10:23 PM, John Hsu <johnhsu@willowgarage.com>wrote:
>>>>>
>>>>>> Hi Pratyush,
>>>>>>
>>>>>> On Tue, May 4, 2010 at 7:04 PM, pratyush jalan <
>>>>>> pratyush.jalan@gmail.com> wrote:
>>>>>>
>>>>>>> Hi Everyone,
>>>>>>>
>>>>>>> 1) I am trying to create my own world file for Gazebo but when I
>>>>>>> launch my world it gives an error that the "Image is not grayscale". I
>>>>>>> created a simple image in paint with a white background and a path with
>>>>>>> black color. I tried using different colors as well but I get the same error
>>>>>>> each time. Can you suggest what might be the problem ?
>>>>>>>
>>>>>>
>>>>>> Please clarify the context... are you trying to use a heightmap?  If
>>>>>> so, the image needs to be saved as a grayscale image (single channel).  Note
>>>>>> that this is not the same as using a color image (multiple channels) with
>>>>>> black and white colors.
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> 2) I am trying to run my controller code on the simplecar.model but
>>>>>>> the problem is the car does not move.
>>>>>>>
>>>>>>
>>>>>> are you using the pr2 mechanism controller stack?  If possible, please
>>>>>> post relevant world/model/launch files, to help with the debugging process.
>>>>>>
>>>>>>
>>>>>>> My code works for the pr2 robot (pr2_simulator). I am able to spawn
>>>>>>> the object in the Gazebo simulator. I get the following message when I spawn
>>>>>>> the object -:
>>>>>>> core service [/rosout] found
>>>>>>> process[spawn_simplecar-1]: started with pid [3814]
>>>>>>> [ INFO] 37.267000000: waiting for gazebo factory, usually launched by
>>>>>>> 'roslaunch `rospack find gazebo`/launch/empty_world.launch'
>>>>>>> [spawn_simplecar-1] process has finished cleanly.
>>>>>>>
>>>>>> log file:
>>>>>>> /home/stk/.ros/log/8f48d09e-57c6-11df-91b7-0024e82035d7/spawn_simplecar-1*.log
>>>>>>>
>>>>>>
>>>>>> looks fine so far...  Did you hit ctrl-c here?
>>>>>>
>>>>>>
>>>>>> thanks,
>>>>>> John
>>>>>>
>>>>>>
>>>>>>> all processes on machine have died, roslaunch will exit
>>>>>>> shutting down processing monitor...
>>>>>>> ... shutting down processing monitor complete
>>>>>>>
>>>>>> done
>>>>>>> Is this an error code ? I wasn't sure because the object is still
>>>>>>> getting spawned in the simulator.
>>>>>>>
>>>>>>> Thanks.
>>>>>>>
>>>>>>> Pratyush
>>>>>>>
>>>>>>> _______________________________________________
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>>>>>>>
>>>>>>>
>>>>>>
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