Add full 3D MLS and carving

A new fusion operator that uses actual MLS of all sources combined with a visibility carving step. Next task is to construct a 4D scene model and fusion with that also.

components/operators/include/ftl/operators/cuda/mls_cuda.hpp

+#ifndef _FTL_CUDA_MLS_HPP_
+#define _FTL_CUDA_MLS_HPP_
+
+#include <ftl/rgbd/camera.hpp>
+#include <ftl/cuda_common.hpp>
+
+namespace ftl {
+namespace cuda {
+
+/**
+ * Basic Moving Least Squares smoothing on a single depth map. Outputs boths
+ * normals and depth values. This is a single iteration of an algorithm that
+ * should iterate 2-3 times. Normals can use some basic estimation as initial
+ * input since they are smoothed by MLS.
+ * 
+ * @param normals_in 4 channel 16-bit float (half).
+ * @param normals_out 4 channel 16-bit float (half).
+ * @param depth_in 1 channel 32-bit float
+ * @param depth_out 1 channel 32-bit float
+ * @param smoothing Gaussian radius in depth units
+ * @param radius Window radius for smoothing
+ * @param camera Camera intrinsics
+ * @param stream Optional CUDA stream
+ */
+void mls_smooth(
+	const cv::cuda::GpuMat &normals_in,
+	cv::cuda::GpuMat &normals_out,
+	const cv::cuda::GpuMat &depth_in,
+	cv::cuda::GpuMat &depth_out,
+	float smoothing,
+	int radius,
+	const ftl::rgbd::Camera &camera,
+	cudaStream_t stream);
+
+/**
+ * Basic Moving Least Squares smoothing on a single depth map. Outputs just the
+ * smoothed normals. This is a single iteration of an algorithm that should
+ * iterate 2-3 times.
+ * 
+ * @param normals_in 4 channel 16-bit float (half).
+ * @param normals_out 4 channel 16-bit float (half).
+ * @param depth_in 1 channel 32-bit float
+ * @param smoothing Gaussian radius in depth units
+ * @param radius Window radius for smoothing
+ * @param camera Camera intrinsics
+ * @param stream Optional CUDA stream
+ */
+void mls_smooth(
+	const cv::cuda::GpuMat &normals_in,
+	cv::cuda::GpuMat &normals_out,
+	const cv::cuda::GpuMat &depth_in,
+	float smoothing,
+	int radius,
+	const ftl::rgbd::Camera &camera,
+	cudaStream_t stream);
+
+}
+}
+
+#endif  // _FTL_CUDA_MLS_HPP_