problem changing line_width_ or point_size_ for LineSet

[cwreynolds]

Checklist

• I have searched for similar issues.
• For Python issues, I have tested with the latest development wheel.
• I have checked the release documentation and the latest documentation (for main branch).

Describe the issue

I cannot see any obvious change when I try to increase line_width_ or point_size_ for LineSet.

I am setting vis.GetRenderOption().line_width_ = 10.0; My code calls Open3D from C++ using a version I built from source in the last new weeks. The main branch minus a few of the most recent commits.

Steps to reproduce the bug

// Test code:

void LineWidthPointSizeTest()
{
    open3d::PrintOpen3DVersion();
    auto lineset = std::make_shared<open3d::geometry::LineSet>();
    lineset->points_ = {{5, 0, 0}, {-5, 0, 0}, {0, 5, 0}, {0, -5, 0}, {0, 0, 5}, {0, 0, -5}};
    lineset->lines_ = {{0, 1}, {2, 3}, {4, 5}};
    lineset->colors_ = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}};
    
    auto vis = open3d::visualization::Visualizer();
    vis.CreateVisualizerWindow();
    vis.AddGeometry(lineset);
    vis.GetRenderOption().line_width_ = 10.0;
    vis.GetRenderOption().point_size_ = 20.0;
    vis.Run();
}

Error message

(visual problem)

Expected behavior

I wanted thicker lines. Setting vis.GetRenderOption().line_width_ = 10.0 made no obvious difference. I also tried setting vis.GetRenderOption().point_size_ = 20.0 and the vertices do not appear any larger than the lines, which themselves appear no wider than the default.

Open3D, Python and System information

- Operating system: macOS 14.6.1
- Python version: 
- Open3D version: 0.18.0+18a47ef
- System architecture: arm64
- Is this a remote workstation?: no
- How did you install Open3D?: build from source
- Compiler version (if built from source): Apple clang version 15.0.0 (clang-1500.3.9.4)

Additional information

By the way, is there a way to use open3d::PrintOpen3DVersion() to get the exact version string "version+main_commit"? (Like: 0.18.0+18a47ef) Does this work from open3d.__version__ in Python?

[weixi234]

I have the similar confusion ，I find the changes invalid:
open3d::visualization::Visualizer visualizer;
visualizer.GetRenderOption().ChangeLineWidth(50.0);
visualizer.GetRenderOption().SetPointSize(5.0);
visualizer.GetRenderOption().line_width_=10.0;
More i find that the documentation for using C++ is particularly poor...

[cwreynolds]

Thanks @weixi234. I don't know how to fix this or work around it. So far, I have just been using the default tiny sizes. For future reference, RenderOption.h lists this information about the ranges and units of these line drawing parameters:

    const double POINT_SIZE_MAX = 25.0;
    const double POINT_SIZE_MIN = 1.0;
    const double POINT_SIZE_STEP = 1.0;
    const double POINT_SIZE_DEFAULT = 5.0;
    const double LINE_WIDTH_MAX = 10.0;
    const double LINE_WIDTH_MIN = 1.0;
    const double LINE_WIDTH_STEP = 1.0;
    const double LINE_WIDTH_DEFAULT = 1.0;

I am new to using Open3D from c++, and yes, the c++ API doc is often unhelpful. Open3D has many helpful usage examples, but they use the Python API. So a c++ user needs to translate, which can be error prone.

[cwreynolds]

Thinking about this just now, I recall a bug in Open3D 0.17.0 (?) where GetViewControl() returned a copy of the ViewControl object, so modifying it had no effect on the view. I tried a quick experiment to verify that my code was in fact modifying the RenderOption object. It looks like it is:

Before:

vis.GetRenderOption().line_width_ = 1
vis.GetRenderOption().point_size_ = 5

After:

vis.GetRenderOption().line_width_ = 10
vis.GetRenderOption().point_size_ = 20