75c947a467
This patch changes the interpolation algorithm utilized by the Keying Screen node to a Gaussian Radial Basis Function Interpolation. This is proposed because the current Voronoi triangulation based interpolation has the following properties: - Not temporally stable since the triangulation can abruptly change as tracking markers change position. - Not smooth in the mathematical sense, which is also readily visible in the artists sense. - Computationally expensive due to the triangulation and naive rasterization algorithm. On the other hand, the RBF interpolation method is temporally stable and continuous, smooth and infinitely differentiable, and relatively simple to compute assuming low number of markers, which is typically the case for keying screen objects. This breaks backward compatibility, but the keying screen is only used as a secondary input for keying in typical compositor setups, so one should expect minimal difference in outputs. Pull Request: https://projects.blender.org/blender/blender/pulls/112480
77 lines
1.8 KiB
C++
77 lines
1.8 KiB
C++
/* SPDX-FileCopyrightText: 2012 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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#pragma once
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#include <string.h>
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#include "COM_MultiThreadedOperation.h"
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#include "DNA_movieclip_types.h"
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#include "BLI_array.hh"
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#include "BLI_listbase.h"
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#include "BLI_math_base.hh"
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#include "BLI_math_vector_types.hh"
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#include "BLI_string.h"
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namespace blender::compositor {
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/**
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* Class with implementation of green screen gradient rasterization
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*/
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class KeyingScreenOperation : public MultiThreadedOperation {
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protected:
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struct MarkerPoint {
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float2 position;
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float4 color;
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};
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MovieClip *movie_clip_;
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float smoothness_;
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int framenumber_;
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Array<MarkerPoint> *cached_marker_points_;
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char tracking_object_[64];
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/**
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* Determine the output resolution. The resolution is retrieved from the Renderer
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*/
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void determine_canvas(const rcti &preferred_area, rcti &r_area) override;
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Array<MarkerPoint> *compute_marker_points();
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public:
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KeyingScreenOperation();
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void init_execution() override;
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void deinit_execution() override;
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void *initialize_tile_data(rcti *rect) override;
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void set_movie_clip(MovieClip *clip)
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{
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movie_clip_ = clip;
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}
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void set_tracking_object(const char *object)
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{
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BLI_strncpy(tracking_object_, object, sizeof(tracking_object_));
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}
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void set_smoothness(float smoothness)
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{
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smoothness_ = math::interpolate(0.15f, 1.0f, smoothness);
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}
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void set_framenumber(int framenumber)
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{
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framenumber_ = framenumber;
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}
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void execute_pixel(float output[4], int x, int y, void *data) override;
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void update_memory_buffer_partial(MemoryBuffer *output,
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const rcti &area,
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Span<MemoryBuffer *> inputs) override;
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};
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} // namespace blender::compositor
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