On Jul 18, 2016, at 10:10 AM, Bokeh coder <michaelsvenna@gmail.com> wrote:
Hi Bryan,
Thank you for your fast response.
I suspected looking into datashader was the way to go.
Do you know if datashader can work with raster data?
I was concerned that it might only work for point-data because i have not really been able to find any raster examples with datashader.
Also, can i do things like invert y-axis using a datashader and link it to other bokeh plots to share eg. panning and zooming properties?
On Monday, July 18, 2016 at 4:41:55 PM UTC+2, Bryan Van de ven wrote:
I also definitely recommend looking into Datashader. You're never going to want to send 700mb (more, realistically, given how Bokeh currently serializes arrays) into the browser. Even if you could, it's far more pixels than can be displayed at once.
Another option is to downsample the full image yourself in a bokeh app, based on the current plot size and bounds, but I would recommend looking at Datashader first.
Bryan
> On Jul 18, 2016, at 9:16 AM, Will Kew <pop...@gmail.com> wrote:
>
> 11000x7000 sounds very large. I suspect you want to use Datashader for this sort of work.
> Unless you plot a 11000x7000 pixel image, you wont see every datapoint anyway, so some form of downsampling is required.
>
> On Monday, 18 July 2016 06:23:47 UTC+1, Bokeh coder wrote:
> Hello, I am interested to know how i can plot VERY large images using the image function in Bokeh?
> I have a matrix of size 11000x7000, which normal matplotlib is able to plot in around 10 seconds using around 700mb ram.
> Bokeh has problems plotting it if i just try to plot using the image function.
> It makes sense if Bokeh is having problems with this since its a lot of data, but i really need to plot this, and even link this plot to plots such that linked zooming and panning is avilable. I furthermore need to reverse the y-axis to have 0,0 in top left corner.
> Using normal Bokeh image function i can achieve this by reversing yrange and set negative dh in image.
>
> So my question is, how can i go about achieving this in Bokeh?
> Do i need to make use of Bokeh server? Datashader? Other?
> Please advice, thank you.
>
>
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So, if the expected interaction mode for your visualization is that the user will be looking at limited spatial sub-regions of the larger dataset, then a tilerenderer makes sense. If, however, the user is going to be regularly changing their level of zoom as part of their interaction, and if there is widely varying information density between different regions of the data/image/map, then it makes sense to use Datashader, because it can faithfully handle that variation in data density, at arbitrary zoom levels.