Plot: Heat Map using Qt

[beecksche]

@fem_dev

For the camera preset have a look here. I would also enable the ortho projection.

You can also disable the selection mode.

[fem_dev]

@beecksche thank you for your help...

I don't know how to apply this setCameraPreset(Q3DCamera::CameraPreset preset) because, in this Qt3Surface example the surface variable doesn't have this setCameraPreset() method.

How can I do that?

[beecksche]

@fem_dev

The function is part of the camera of the current scene:

Q3DSurface *surface;
surface->scene()->activeCamera()->setCameraPreset()

https://doc.qt.io/qt-5/qtdatavisualization-scatter-example.html#setting-up-the-graph

[fem_dev]

@beecksche perfect! It works great! Thank you!

Could you please help me a little bit more?
In this post above, I said that:

@fem_dev said in Plot: Heat Map using Qt:

I read th Qt documentation (link here) and it said that:
End users can interact with the rendered graph by using either the mouse or touch to rotate, zoom, or select data.
Graphs can be rotated freely by holding down the right mouse button and moving the mouse.

In this example source-code I didn't found any references to the setRotationEnabled(bool enable) (described here)

QUESTION:
a) What I have to do to get the rotation interaction working in this Qt3DSurface example?

[fem_dev]

@fem_dev I got it! Is a right-click event! Thank you all!

[fem_dev]

To finish my questions ins this post, I would like to compare the Qt3DSurface graphical result and my target graphical result:

If I open the Qt 3DSurface example and use this:

m_graph->scene()->activeCamera()->setCameraPreset(Q3DCamera::CameraPresetDirectlyAbove)

and change the line:

m_sqrtSinSeries->setDrawMode(QSurface3DSeries::DrawSurfaceAndWireframe);

to:

m_sqrtSinSeries->setDrawMode(QSurface3DSeries::DrawSurface);

I got this graph output:

My "target image style" is:

So, in the 3DSurface example the image appears divided in triangles, where each triangle have a different color. Because of this method, the final image result IS NOT so "well defined" (color smooth transition) and doesn't have a "high resolution appearance" like the "target image style" above.

a) Is there a way to get the same "well defined pixel resolution" using Q3DSurface?
b) The "target image" have a right-side color pallet. How can I do that in Qt using Q3DSurface?

[Trap]

Hi,

I have added a Qt implementation of the HeatMap that you can find in this repo.

Best regards,
Ahmed Trabelsi

[SGaist]

@Trap hi and welcome to devnet,

Thanks for the class !

There are some small improvements you can do to it.

Technically, you do not need to keep your QImage nor QPixmap as member variables since you will replace them with new ones when changing the data.

This will also remove the current memory leak you have with imageD. There's usually no need to allocate them on the heap.

[__mk__]

5 years have passed and Qt still doesn't natively support heatmaps in QCharts.

There are some decent solutions in this thread, but I wasn't happy with either of them.
I've created a minimal, self contained heatmap method in case anyone needs it:

https://gist.github.com/mathklk/f1d8d0c5a82a84a637a260edfc76a145

[Joe von Habsburg]

You can use Qwt. I agree with you. QCharts so low.