I am developing on an application based on VTK and GDCM for viewing medical (DICOM) images.
The application has three windows that respectively show XY, YZ and XZ orientations (axial, coronal and sagittal). This is similar to the 2D views here. I use vtkImageViewer2 for this. The voxel values of the DICOM images are passed on to an instance of vtkImageData. The instance of the vtkImageData is the passed on the to three instances of vtkImageViewer2 (let's use imageViewerXY, imageViewerYZ and imageViewerXZ). The orientation of each instance of vtkImageViewer2 is then set using SetSliceOrientationToXY(), SetSliceOrientationToYZ() and SetSliceOrientationToXZ(). Without the mask, I can see the slices, couple the windows and scroll through the images perfectly fine.
To add the mask so that it is shown in the three views, I use vtkImageActor. For the XY view, which is the default view, this works fine. I update the instance of vtkImageActor, which I call maskActorXY based on the mouse events of XY window as follows:
int extent[6];
imageViewerXY->GetImageActor->GetDisplayExtent(extent);
maskActorXY->SetDisplayExtent(extent);
maskActorXY->Update();
imageViewerXY->GetRenerer->Render();
Now, when I do the same for the other two windows so that I can see the 3D mask in the other two orientations, for example for the YZ orientation,
imageViewerYZ->GetImageActor->GetDisplayExtent(extent);
maskActorYZ->SetDisplayExtent(extent);
maskActorYZ->Update();
imageViewerYZ->GetRenerer->Render();
I get an error message that traces to vtkImageData and accessing pixel values outside of the extent set for the mask actor.
I have a limited familiarity with VTK, but looking at the source code of vtkImageViewer2 (see UpdateDisplayExtent() on line 341), I don't understand why pixel values out side of the specified display extent are requested from my instances of vtkImageActor that represent the mask.
I found a solution. Since I am not familiar with VTK, I may not be able to provide a clear explanation. All that I needed were the following two lines for each mask to force its mappers to face the camera:
maskActorYZ->GetMapper()->SetAtFocalPointOn();
maskActorYZ->GetMapper()->SliceFacesCameraOn();
(see [vtkImageMapper3D][1] class.)
Related
I am tweaking the Areas Example project from SwiftCharts and I am running into the issue where the point indicators are getting cut off like so:
In the github issues a found this and this other issue where the solutions were to set chartSettings.clipInnerFrame = false
However, when I do this the the area color awkward shape also becomes visible like so:
How can I get the whole shape of the points but all the other stuff?
You have to pass to the ChartPointsViewsLayer with the points clipViews: false (see example). ChartSettings.clipInnerFrame has to be true (i.e. the default). This way only the layer with the points is clipped.
Finally, if you want to clip the unclipped points layer (to limit the area outside of the chart where they are displayed), you can do it passing a custom rectangle, like here (this setting is admittedly not very intuitive).
I work with UnstructuredGrid and I want to triangulate it like in Paraview (when I clicked for model).
How I can do it?
I tried vtkDelaunay3D, vtkDelaunay2D and vtkTriangleFilter.
vtkDelaunay3D :
I've transformed UnstructuredGrid to vtkPolyData, after used vtkCleanPolyData and vtkDelaunay3D. It's not worked. It's crushed with this warning :
vtkMath.cxx: Unable to factor linear system
vtkDelaunay2D :
Similarly I used vtkDelaunay2D, but result is not good for me.
Also I use vtkTriangleFilter, it's result not good for me too.
When you click (or interact) in ParaView, ParaView is rendering a simplified geometry -- not simply a triangulated geometry. The filter it uses to do that is vtkQuadricClustering. Apply the vtkGeometryFilter first to your unstructured grid to convert your vtkUnstructuredGrid to a vtkPolyData. Then connect it to vtkQuadricClustering. You can play with parameters in vtkQuadricClustering to control the simplification.
I am trying to add a target (bullseye) to an image without the use of importing python functions, it is proving to be rather difficult however I believe I need to define a circle through use of code. It should be done by changing the pixels as opposed to importing functions.
Thanks
Needs to be in the centre of an image
You will need to add more information here - how is your image represnted in Python? Normally for porduction code, dealing with images is done through 3rd party modules, each of which have a way to draw or change different pixels. If you are using none you have to define your image reading and writting code (or a way to display the image on the screen).
Anyway, doing all of that without any "importing" will be quite artificial, though feasible.
Maybe you should use pnm files which have a minimum of encoding required.
That said, you could represent the image in memory as a bytesarray object, and use math.sin and math.cos (you will have to import those, or resort to a "raytracing" approach which can render the circle based on x**2 + y * 2 = r ** 2 ) to draw your circle.
I'm working with nokia HERE maps and I want to add an additional layer of visualization graphics on top of a map. Since the possibilities to interact, manipulate and customize the graphics created by the HERE api are limited, I would like to work with d3.js/SVG for my visualizations.
My straight forward and obvious solution would have been to just add an absolute positioned SVG element on top of the map and giving it the same dimensions. But of course that takes every possibility to interact with the map. Is there any solution to add an overlay to the map which allows me to put SVG on it while maintaining the full interactivity (panning, zooming, clicking) of the map? Also it should be possible to interact with the SVG.
I know that there is a possibility to add a custom overlay of tiles provided by a tile server to HERE maps but that's not really what I'm looking for. I'm looking for something like the solution google has to offer to this problem. A set of custom layers which are always in sync with the corresponding map and have their own initialize, draw and remove methods. Is there something similar for HERE maps?
I think you are after the nokia.maps.map.provider.CanvasProvider class. This class provides a ground overlay bound to a specific area which offers a draw() method. The attach() method is the equivalent of your intialize I think, and you can refresh the overlay using update().
Depending upon your use case, I've also found the following techniques useful regarding SVG, Images and HERE Maps:
For an SVG marker which is anchored to a point and doesn't resize
use: SVG Markers
Alternatively override the Marker class and write using the low
level graphics commands to add flexibility to the rendering of a
marker anchored to a point. Like this: Defaced Marker
To add an image bound to a specific area use the ImageProvider class
To add a series of tiled images from a TMS (Tile Map Service) use the ImgTileProvider class
Alternatively if the [zoom][col][row] is useful to you and you
want to write SVG based stuff yourself try something like this example - which combines
SVG with 256x256 pixel markers.
Note that the HERE Maps API for JavaScript only supports SVG Tiny.
A class like the old nokia.maps.map.provider.CanvasProvider isn't even available on the new v3 API from Here.
Your best bet is on Leaflet using custom providers loading Here map tiles. Then you just load this Custom Overlay class and you're all set to draw D3, WebGL, whatever you need. Leaflet only loads the tiles from the providers and exposes some simple APIs. You will not have to deal with any of the providers' APIs.
Just don't forget to add your app_id and app_code to the provider class.
I used Apple's AVEdit-Demo, tweaked it a little and was able to add CALayers with animations and images to the video-composition. So far, this works fine.
It uses AVVideoComposition and AVPlayer/AVPlayerItem to merge videos (and show them - the export rendering is a little different).
I added a layer with a png with some transparent areas, sort of like a mask, that hides parts of the video. Now I need to move the video-layer, so I can adjust the hidden parts (a.k.a. the visible part). The Mask covers the whole screen (in a CALayer), so moving the Mask-Layer isn't an option.
I didn't find any properties or methods, to adjust the position of the video-layer...
Any Ideas?
Found it...
I had to access the AVMutableCompositionTrack in the AVMutableVideoComposition and set the preferredTransform there (CGAffineTransformTranslate).
However - the Docs state, that this should be possible in a AVMutableComposition as well (AVAssetTrack setPreferredTransform).
I couldn't get this to work, though.