Displaying a large QImage on ImageOverlay

FatmaAkdemir

We have a constantly changing radar image which is 8000x8000 pixels. Whenever the radar image changes, a slot function  is executed as below:

void MainMapWidget::slotRadarImageChanged(const QImage &image){
	 std::unique_ptr<ImageFrame> m_imageFrame = std::make_unique<ImageFrame>(image, m_ImageOverlayEnvelope, this);
	 m_imageOverlay->setImageFrame(m_imageFrame.get());
}

This slotRadarImageChanged is not being called after each radar echo, instead we wait 30 echoes to be received and after that imageChanged signal is emitted. We detected that this function occupies CPU so much, causing a bottleneck in our program. If the image is 2000x2000 it does not cause any delays.

 

In short, we want to find a way to optimize passing our QImage to ImageOverlay. If there are any other alternative ways to do this, please share with us.

KoushikHajra

Hi FatmaAkdemir,

I want to make sure that I understand your question. So, this slot is not being called every time there's a radar echo and an image changes. It's called once in every 30 times. Is that right? 

So, it only seems to be a bottleneck when the image is really high resolution (8kx8k)? There could be some optimization we could do on our end for this. We haven't had anyone request something with that high resolution. In our internal testing, we have used images upto 1k resolution. Is it possible to share an image with us so that we could take a look? I think the CPU usage is all about trying to load that large image. 

What you're doing is correct and should work. So, I will log a bug in any case for us to take a look and see what's going on.