Roughly the same render times on all HW configurations

[MaxM1211]

Hello everyone & happy new year

I am currently working on a Trame application that contains three slicing views and a volume viewer (SSR).
As this is part of my bachelor thesis, I want to measure the rendering times on different hardware configurations on Azure VMs.

For the measurement, I record the start and stop events of the animation on the server. (Are there more suitable events?)

Unfortunately, I get roughly the same animation times from each server, even though I have fairly powerful servers.

Tested with vtk-osmesa and different setups:

• 2 vCPU, 4 GiB
• Something in between
• 32 vCPU, 64 GiB

And even when using vtk-egl with a graphics card, the rendering time remains the same.
nvidia-smi shows little to no GPU usage.

Are there any reasons or explanations for these observations?

Thank you very much!

Context:
Ubuntu 20.04
Volume loaded from DICOM
Headless

[jourdain]

See EGL caution section in case you are running into the same issue I ran into.

[MaxM1211]

I should be using the VtkRemoteView

Here are the relevant code parts:

Imports

#!/usr/bin/env python

from events import * # My event handling

# Web imports
import os
from trame.app import get_server
from trame.ui.vuetify import SinglePageLayout
from trame.widgets import vtk, vuetify

# noinspection PyUnresolvedReferences
from vtkmodules.vtkInteractionStyle import (
    vtkInteractorStyleImage,
    vtkInteractorStyleTrackballCamera,
)

from vtkmodules.vtkCommonDataModel import vtkPiecewiseFunction
from vtkmodules.vtkIOImage import (
    vtkDICOMImageReader,
)
from vtkmodules.vtkRenderingVolume import vtkFixedPointVolumeRayCastMapper

# noinspection PyUnresolvedReferences
from vtkmodules.vtkRenderingVolumeOpenGL2 import vtkOpenGLRayCastImageDisplayHelper

from vtkmodules.vtkRenderingCore import (
    vtkRenderWindow,
    vtkRenderWindowInteractor,
    vtkRenderer,
    vtkImageSlice,
    vtkImageSliceMapper,
    vtkVolume,
    vtkVolumeProperty,
    vtkColorTransferFunction,
)

from vtkmodules.vtkIOXML import vtkXMLImageDataReader

# Required for rendering initialization, not necessary for
# local rendering, but doesn't hurt to include it
import vtkmodules.vtkRenderingOpenGL2  # noqa
...

Remote View Setup (1 out of 4)

...
    with layout.content:
        with vuetify.VContainer(
            fluid=True,
            classes="pa-0 fill-height fill-width",
        ):
            with vuetify.VCol(style="height: 100%"):
                with vuetify.VRow(
                    classes="pa-0 ",
                    style="height:50%",
                ):
                    view = (
                        vtk.VtkRemoteView(
                            renderWindow_axial,
                            ref="axial",
                            interactive_quality=60,
                            interactor_events=(
                                "events",
                                events_list,
                            ),
                            StartAnimation=StartAnimation,
                            EndAnimation=EndAnimation,
                        ),
                    )
...

[jourdain]

Indeed and I'm not sure what could be going on. Normally accelerated (GPU) rendering should be very good.

[MaxM1211]

Maybe the dataset is to small like in the original question, so vtk doesn't need to use the gpu much.

Are there maybe better events to capture than the Animation ones?

Or is there a way to get performance information in general? Like latency, generated frames/ fps, ...

Thanks again for all the help 👍🏼

[jourdain]

I'm not sure what you see but you should expect 25-30 fps with maybe a 30ms latency.

[MaxM1211]

I will check that. Thanks.

I will update this conversation when more questions come up, or when I'm done with the bachelor :-D

And it seems like the solution again was getting a higher resolution of the volume. On my 2k display I got the expected result: osmesa - times > egl - times

Thanks for now 👍🏼