Time-gated rendering (online)

This tutorial renders the Cornell box from Time-gated rendering in an interactive window. The image converges while the camera stays still, and the settings and the camera can be changed while it runs.

1. Open a window and load the scene

With a window, the frame buffer takes the window size, so no resize_frame_buffer call is needed.

import falcorcomp as falcor

testbed = falcor.Testbed(create_window=True, width=1024, height=1024, title="Time-gated Cornell box")
testbed.load_scene("cornell-box/scene-v4-nolight.pbrt")
testbed.scene.camera.aspectRatio = 1.0
testbed.clock.pause()

2. Build the render graph

The graph is the offline one. The window shows the first marked output, so only the tone-mapped image is marked.

graph = testbed.create_render_graph("TimeGated")
graph.create_pass("VBuffer", "VBufferRT", {"samplePattern": "Center", "sampleCount": 1})
graph.create_pass("Laser", "LaserLight", {
    "laserPosition": [0.0, 1.7, 6.8], "laserDirection": [0.0, 0.0, -1.0],
    "laserPower": [170.0, 120.0, 40.0], "laserAngle": 0.0,
})
graph.create_pass("Tracer", "TimeGatedPathTracerInline", {
    "samplesPerPixel": 16, "maxBounces": 6, "computeDirect": False,
    "timeGateMode": "box", "timeGateWindow": 0.1, "timeMin": 17.337, "timeMax": 17.337,
})
graph.create_pass("Accumulate", "AccumulatePass", {"precisionMode": "SingleCompensated"})
graph.create_pass("ToneMapper", "ToneMapper", {"autoExposure": False})

graph.add_edge("VBuffer.vbuffer", "Tracer.vbuffer")
graph.add_edge("VBuffer.viewW", "Tracer.viewW")
graph.add_edge("Laser", "Tracer")
graph.add_edge("Tracer.color", "Accumulate.input")
graph.add_edge("Accumulate.output", "ToneMapper.src")
graph.mark_output("ToneMapper.dst")  # shown in the window
testbed.render_graph = graph

3. Run

run() renders frames until the window is closed.

testbed.run()

Controls

• Camera: drag with the mouse to look around; W/A/S/D move, Q/E move down and up (hold Shift to move faster, Ctrl to move slower).

• Settings: the Render Graph window has a section per pass. Under Tracer, Time gate sets the gate center, window and kernel; Shift gate moves the gate one step per frame from Gate min to Gate max, so the light front sweeps through the scene. The sampling method is below it. Under Laser, the laser position, direction, cone angle and type can be edited.

• Window: F1 shows the help, F2 hides the UI, Esc exits.

Changing a setting or moving the camera restarts accumulation. With Shift gate on, every gate step restarts it too, so each gate shows a single frame of samplesPerPixel samples.

The full script: time_gated_online.py.