[osg-users] osg::Image::setImage problem

[Robert Osfield]

HI Evan,

My best guess is that the packing of the data in each row is out, as
your Image::setData(..) call doesn't supply all the parameters
explicitly it will default to a packing of 1 byte.

For instance if the packing for your source data is 4 bytes, and all
you previous image data has a width with multiple of 4 then there
won't be any mismatch when using a 1 byte packing as it will select
the same width.  However, if you use a width such as 3 then the source
data with a 4 byte packing would round up to 4 bytes width, but the
osg::Image::setImage() call you are using says just use 1 byte packing
so selects a width of 3.  This will result in a each successive row
starting 1 byte off and leading to the "twist" you see.

Check the spec of your image reading code/file format to see what the
row packing is.  Also have a look at the docs for
osg::Image::setImage(..), note the optional packing and rowLength
parameters.

Robert






On 18 February 2017 at 16:38, Evan Tsai <evanyftsai at gmail.com> wrote:
> Thank you very much for helping.  Below is how we make the call.
>
> This has been working fine until very recently we received scan data from some CBCT scanners that we haven't encountered before.  However those scans could be viewed correctly in all popular DICOM viewers in the market.  As mentioned, I also took the pixel data and dumped it into a .bmp file, which looks correct.  So the only possibility seems to be that we are missing some setting here......
>
> I did try changing the texture coordinates around but that doesn't change the twisted nature of the display.
>
> I also tried changing `packing' from 1 to 0 but that crashes the software.
>
> Is there anything in particular that one needs to set for `rowLength'?
>
>
>
>         osg::Geode* pGeode = new osg::Geode;
>
>         osg::Vec3 v1(pBottomLeft[0], pBottomLeft[1], pBottomLeft[2]);
>         osg::Vec3 v2(pBottomRight[0], pBottomRight[1], pBottomRight[2]);
>         osg::Vec3 v3(pTopRight[0], pTopRight[1], pTopRight[2]);
>         osg::Vec3 v4(pTopLeft[0], pTopLeft[1], pTopLeft[2]);
>
>         osg::Geometry* geom = new osg::Geometry;
>         geom->setDataVariance(osg::Object::DYNAMIC);
>         osg::Vec3Array* vertices = new osg::Vec3Array(4);
>         (*vertices)[0] = v1;
>         (*vertices)[1] = v2;
>         (*vertices)[2] = v3;
>         (*vertices)[3] = v4;
>         geom->setVertexArray(vertices);
>
>         osg::Vec2Array* texcoords = new osg::Vec2Array(4);
>         (*texcoords)[0].set(0.0f, 0.0f);
>         (*texcoords)[1].set(1, 0.0f);
>         (*texcoords)[2].set(1, 1);
>         (*texcoords)[3].set(0.0f, 1);
>
>         geom->setTexCoordArray(0, texcoords);
>
>         osg::ref_ptr<osg::Vec3Array> normals = new osg::Vec3Array(1);
>         (*normals)[0].set(0.0f, -1.0f, 0.0f);
>         geom->setNormalArray(normals, osg::Array::BIND_OVERALL);
>         osg::Vec4Array* colors = new osg::Vec4Array(1);
>         (*colors)[0].set(1.0f, 1.0f, 1.0f, 1.0f);
>         geom->setColorArray(colors, osg::Array::BIND_OVERALL);
>
>         geom->addPrimitiveSet(new osg::DrawArrays(GL_QUADS, 0, 4));
>         geom->setUseDisplayList(false);
>         osg::ref_ptr<osg::Image> img = new osg::Image;
>
>         img->setImage(image.GetWidth(), image.GetHeight(), 1,
>                 GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, image.GetPixelData(),
>                 osg::Image::USE_NEW_DELETE);
>
>         //osg::ref_ptr<osg::Image> img = osgDB::readRefImageFile("C:\\Users\\rupeshb\\Pictures\\error.bmp");
>
>         //osg::ref_ptr<osg::Image> img = osgDB::readRefImageFile(filename);
>
>         osg::ref_ptr<osg::Texture2D> texture = new osg::Texture2D(img);
>         texture->setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR);
>         texture->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
>         osg::ref_ptr<osg::TexMat> texmat = new osg::TexMat;
>         texmat->setScaleByTextureRectangleSize(true);
>         // setup state
>         osg::ref_ptr<osg::StateSet> state = geom->getOrCreateStateSet();
>         state->setTextureAttributeAndModes(0, texture, osg::StateAttribute::ON | osg::StateAttribute::PROTECTED);
>         state->setTextureAttributeAndModes(0, texmat, osg::StateAttribute::ON | osg::StateAttribute::PROTECTED);
>
>         state->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
>
>         pGeode->addDrawable(geom);
>         addChild(pGeode);
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=70254#70254
>
>
>
>
>
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