Merge pull request #339 from syncle/texture_map_optimization

Color map optimization #230

Author: qianyizh

docs/_static/Advanced/color_map_optimization/initial.png

@@ -0,0 +1,180 @@
+.. _color_map_optimization:
+
+Color Map Optimization
+-------------------------------------
+
+Consider color mapping to the geometry reconstructed from depth cameras. As color and depth frames are not perfectly aligned, the texture mapping using color images is subject to results in blurred color map. Open3D provides color map optimization method proposed by [Zhou2014]_. Before begin, download fountain dataset from `here <https://drive.google.com/open?id=1eT45y8qw3TLED2YY9-K1Ot6dQuF9GDPJ>`_. The following script shows an example of color map optimization.
+
+.. code-block:: python
+
+    from py3d import *
+    from trajectory_io import *
+    import os, sys
+    sys.path.append("../Utility")
+    from common import *
+
+    path = "[set_this_path_to_fountain_dataset]"
+    debug_mode = False
+
+        if __name__ == "__main__":
+            set_verbosity_level(VerbosityLevel.Debug)
+
+            # Read RGBD images
+            rgbd_images = []
+            depth_image_path = get_file_list(
+                    os.path.join(path, "depth/"), extension = ".png")
+            color_image_path = get_file_list(
+                    os.path.join(path, "image/"), extension = ".jpg")
+            assert(len(depth_image_path) == len(color_image_path))
+            for i in range(len(depth_image_path)):
+                depth = read_image(os.path.join(depth_image_path[i]))
+                color = read_image(os.path.join(color_image_path[i]))
+                rgbd_image = create_rgbd_image_from_color_and_depth(color, depth,
+                        convert_rgb_to_intensity = False)
+                if debug_mode:
+                    pcd = create_point_cloud_from_rgbd_image(rgbd_image,
+                            PinholeCameraIntrinsic.get_prime_sense_default())
+                    draw_geometries([pcd])
+                rgbd_images.append(rgbd_image)
+
+            # Read camera pose and mesh
+            camera = read_pinhole_camera_trajectory(os.path.join(path, "scene/key.log"))
+            mesh = read_triangle_mesh(os.path.join(path, "scene", "integrated.ply"))
+
+            # Before full optimization, let's just visualize texture map
+            # with given geometry, RGBD images, and camera poses.
+            option = ColorMapOptmizationOption()
+            option.maximum_iteration = 0
+            color_map_optimization(mesh, rgbd_images, camera, option)
+            draw_geometries([mesh])
+            write_triangle_mesh(os.path.join(path, "scene",
+                "color_map_before_optimization.ply"), mesh)
+
+            # Optimize texture and save the mesh as texture_mapped.ply
+            # This is implementation of following paper
+            # Q.-Y. Zhou and V. Koltun,
+            # Color Map Optimization for 3D Reconstruction with Consumer Depth Cameras,
+            # SIGGRAPH 2014
+            option.maximum_iteration = 500
+            option.non_rigid_camera_coordinate = True
+            color_map_optimization(mesh, rgbd_images, camera, option)
+            draw_geometries([mesh])
+            write_triangle_mesh(os.path.join(path, "scene",
+                "color_map_after_optimization.ply"), mesh)
+
+Input
+````````````````````````
+
+.. code-block:: python
+
+    # read RGBD images
+    rgbd_images = []
+    depth_image_path = get_file_list(
+            os.path.join(path, "depth/"), extension=".png")
+    color_image_path = get_file_list(
+            os.path.join(path, "image/"), extension=".jpg")
+    assert(len(depth_image_path) == len(color_image_path))
+    for i in range(len(depth_image_path)):
+        depth = read_image(os.path.join(depth_image_path[i]))
+        color = read_image(os.path.join(color_image_path[i]))
+        rgbd_image = create_rgbd_image_from_color_and_depth(color, depth,
+                convert_rgb_to_intensity=False)
+        if debug_mode:
+            pcd = create_point_cloud_from_rgbd_image(rgbd_image,
+                    PinholeCameraIntrinsic.get_prime_sense_default())
+            draw_geometries([pcd])
+        rgbd_images.append(rgbd_image)
+
+This script reads color and depth image pairs and makes ``rgbd_image``. Note that ``convert_rgb_to_intensity`` flag is ``False``. This is to preserve 8-bit color channels instead of using single channel float type image.
+
+It is always good practice to visualize RGBD image before applying it to color map optimization. ``debug_mode`` switch is for visualizing RGBD image.
+
+.. code-block:: python
+
+    # read camera pose and mesh
+    camera = read_pinhole_camera_trajectory(os.path.join(path, "scene/key.log"))
+    mesh = read_triangle_mesh(os.path.join(path, "scene", "integrated.ply"))
+
+The script reads camera trajectory and mesh.
+
+.. code-block:: python
+
+    option = ColorMapOptmizationOption()
+    option.maximum_iteration = 0
+    color_map_optimization(mesh, rgbd_images, camera, option)
+    draw_geometries([mesh])
+    write_triangle_mesh(os.path.join(path, "scene",
+        "color_map_before_optimization.ply"), mesh)
+
+To visualize how the camera poses are not good for color mapping, this script intentionally set the iteration number as 0, which means no optimization. ``color_map_optimization`` paints a mesh using corresponding RGBD images and camera poses. Without optimization, the texture map is blurred.
+
+.. image:: ../../_static/Advanced/color_map_optimization/initial.png
+    :width: 300px
+
+.. image:: ../../_static/Advanced/color_map_optimization/initial_zoom.png
+    :width: 300px
+
+Rigid Optimization
+```````````````````````````````
+
+The next step is to optimize camera poses to get a sharp color map.
+
+.. code-block:: python
+
+    option.maximum_iteration = 500
+    option.non_rigid_camera_coordinate = True
+    color_map_optimization(mesh, rgbd_images, camera, option)
+    draw_geometries([mesh])
+    write_triangle_mesh(os.path.join(path, "scene",
+        "color_map_after_optimization.ply"), mesh)
+
+The script sets ``maximum_iteration = 500`` for actual iterations. The optimization displays the following energy profile.
+
+.. code-block:: shell
+
+    [ColorMapOptimization] :: Rigid Optimization
+    [Iteration 0001] Residual error : 25777.372725 (avg : 0.004998)
+    [Iteration 0002] Residual error : 25620.681829 (avg : 0.004967)
+    [Iteration 0003] Residual error : 25463.806101 (avg : 0.004937)
+    :
+    [Iteration 0498] Residual error : 11550.014763 (avg : 0.002255)
+    [Iteration 0499] Residual error : 11549.850827 (avg : 0.002255)
+    [Iteration 0500] Residual error : 11550.062068 (avg : 0.002255)
+
+Residual error implies inconsistency of image intensities. Lower residual leads better color map quality. By default, ``ColorMapOptmizationOption`` enables rigid optimization. It optimizes 6-dimentional pose of every cameras.
+
+.. image:: ../../_static/Advanced/color_map_optimization/rigid.png
+    :width: 300px
+
+.. image:: ../../_static/Advanced/color_map_optimization/rigid_zoom.png
+    :width: 300px
+
+Non-rigid Optimization
+```````````````````````````````````
+
+For better alignment quality, there is an option for non-rigid optimization. To enable, simply add
+
+.. code-block:: python
+
+    option.non_rigid_camera_coordinate = True
+
+before calling ``color_map_optimization``. Besides 6-dimentional camera poses, non-rigid optimization even consider local image warping represented by anchor points. This adds even more flexibility and leads higher quality color mapping. The residual error is smaller than the case of rigid optimization.
+
+.. code-block:: shell
+
+    [ColorMapOptimization] :: Non-Rigid Optimization
+    [Iteration 0001] Residual error : 25777.372725, reg : 0.000000
+    [Iteration 0002] Residual error : 25330.445704, reg : 13.005639
+    [Iteration 0003] Residual error : 24885.912182, reg : 40.000765
+    :
+    [Iteration 0498] Residual error : 7585.606850, reg : 3294.124184
+    [Iteration 0499] Residual error : 7585.274846, reg : 3294.887659
+    [Iteration 0500] Residual error : 7583.972930, reg : 3294.634065
+
+Results of non-rigid optimization follow.
+
+.. image:: ../../_static/Advanced/color_map_optimization/non_rigid.png
+    :width: 300px
+
+.. image:: ../../_static/Advanced/color_map_optimization/non_rigid_zoom.png
+    :width: 300px

docs/_static/Advanced/color_map_optimization/initial_zoom.png

@@ -8,6 +8,7 @@ Advanced
     fast_global_registration
     multiway_registration
     rgbd_integration
+    color_map_optimization
     customized_visualization
     non_blocking_visualization
     interactive_visualization

docs/_static/Advanced/color_map_optimization/non_rigid.png

@@ -13,7 +13,8 @@ Reference
 .. [Rasu2009] R. Rusu, N. Blodow, and M. Beetz, Fast Point Feature Histograms (FPFH) for 3D registration, ICRA, 2009.
 .. [Rusinkiewicz2001] S. Rusinkiewicz and M. Levoy. Efficient variants of the ICP algorithm. In 3-D Digital Imaging and Modeling, 2001.
 .. [Silberman2012] N. Silberman, D. Hoiem, P. Kohli and R. Fergus, Indoor Segmentation and Support Inference from RGBD Images, ECCV, 2012.
-.. [Song2015] S. Song, S. Lichtenberg, and J. Xiao,    SUN RGB-D: A RGB-D Scene Understanding Benchmark Suite, CVPR, 2015.
+.. [Song2015] S. Song, S. Lichtenberg, and J. Xiao, SUN RGB-D: A RGB-D Scene Understanding Benchmark Suite, CVPR, 2015.
 .. [Steinbrucker2011] F. Steinbrucker, J. Sturm, and D. Cremers, Real-time visual odometry from dense RGB-D images, In ICCV Workshops, 2011.
 .. [Strum2012] J. Sturm, N. Engelhard, F. Endres, W. Burgard and D. Cremers, A Benchmark for the Evaluation of RGB-D SLAM Systems, IROS, 2012.
+.. [Zhou2014] Q.-Y. Zhou, and V. Koltun, Color Map Optimization for 3D Reconstruction with Consumer Depth Cameras, SIGGRAPH, 2014.
 .. [Zhou2016] Q.-Y. Zhou, J. Park, and V. Koltun, Fast Global Registration, ECCV, 2016.