These are chat archives for openseadragon/openseadragon

2nd
Jun 2016
Ignacio Tartavull
@tartavull
Jun 02 2016 21:09
Hey I've just started using openseadragon
And I'm trying to use to visualize a large stack of images
It would be something very similar to sequence mode
Ian Gilman
@iangilman
Jun 02 2016 21:11
Do you want to see them all at the same time?
Ignacio Tartavull
@tartavull
Jun 02 2016 21:12
not just one at the time. My only problem with the sequence mode is that the transitions are not that smooth
compare to transitioning between images when panning
Ian Gilman
@iangilman
Jun 02 2016 21:13
So you want to pan between them? or fade between them?
Ignacio Tartavull
@tartavull
Jun 02 2016 21:14
Here is a concrete implementation of what I need
and to rephrase the question:
I noticed(without knowing details about it) that the 2d panning feels really fast, but going back and forth between slices (by using arrows in the left) does not
Ignacio Tartavull
@tartavull
Jun 02 2016 21:20
I was wondering if any of you know of a faster way of transitioning between very similar images
VoidVolker
@VoidVolker
Jun 02 2016 21:24
@tartavull just render images in background frame/buffer and then render when you need
Ignacio Tartavull
@tartavull
Jun 02 2016 21:27
Thanks @VoidVolker , do you know of any example where that is implemented?
VoidVolker
@VoidVolker
Jun 02 2016 21:29
nop
it is well know mechanism
Ignacio Tartavull
@tartavull
Jun 02 2016 21:31
Great, thank you for the pointer. I'll tested out
Ian Gilman
@iangilman
Jun 02 2016 21:39
@tartavull In that example I see a little flash between when I'm switching with the arrows... is that what you're talking about?
BTW, you might find these of use: http://codepen.io/collection/APoyjJ/#
Ignacio Tartavull
@tartavull
Jun 02 2016 21:40
yes, that exactly the problem. It might seem foolish to focus in such an small flash but is actually quite important
Ian Gilman
@iangilman
Jun 02 2016 21:40
I definitely understand; it affects your ability to spot differences between slides.
Ignacio Tartavull
@tartavull
Jun 02 2016 21:41
The main way of exploring this images for us, is to focus into a tiny process and then navigate through the stack
to follow this little process through this "movie"
Ian Gilman
@iangilman
Jun 02 2016 21:41
This is definitely a limitation of our current sequence mode.
Ignacio Tartavull
@tartavull
Jun 02 2016 21:41
exactly
we would like to see, let's say 20 frames per second, to have a good usability
Ian Gilman
@iangilman
Jun 02 2016 21:42
So rather than using sequence mode, you'll need to use http://openseadragon.github.io/examples/multi-image/ and manage the images yourself
How many frames in total for a scene?
Ignacio Tartavull
@tartavull
Jun 02 2016 21:43
usually around a thousand
probably more in the future
Ian Gilman
@iangilman
Jun 02 2016 21:43
What you can do is load all the images at once and lay them all over each other. Then manage the opacity of them so that only the one you currently want to see is visible.
You'll want to preload a few ahead; at the moment the best way to do that is set their opacity to something not quite 0, like 0.001... that triggers the loading but isn't strong enough to be visible (especially if it's layered below the others anyway).
With a thousand images you definitely don't want to preload everything at once, so you'll have to be smart about when you preload.
You probably can't do the entire 1000 at 20 frames per second in one shot, just because of the speed of the network.
BTW, to be sure the next image is loaded, you might want something like this (still in development): openseadragon/openseadragon#723
... though you can get away without it.
... and this is the one for a better preloading mechanism than the opacity trick: openseadragon/openseadragon#821
Ignacio Tartavull
@tartavull
Jun 02 2016 21:49
This is amazingly helpful @iangilman
I can't calculate how many hours of work you saved me
but a lot
Ian Gilman
@iangilman
Jun 02 2016 21:50
:)
Hopefully so!
Let me know how it goes... you'll probably have more questions along the way.
Ignacio Tartavull
@tartavull
Jun 02 2016 21:52
I will let you know, and probably come back for help soon
Ian Gilman
@iangilman
Jun 02 2016 21:52
:thumbsup: