grid_generator.py

grid_generator.py generates very simple 2D grid of RigidTransform[]

parameters

• Optional: scan_id (autogenerated if not provided)
• Required: center_x, center_y, grid_size_x, grid_size_y, grid_spacing, z_height

relevant schema

• schema/Scan/Scan.py
• schema/RigidTransform/RigidTransform.py

---

Rotations

if optional params are provided, the rotations should be applied to each pose in the grid.

For our rotations about Z axis, we will use the following convention: —bracket_range_A_yaw_deg (float) —step_size_A_deg (float)

For our rotations about Y axis, we will use the following convention: —bracket_range_B_pitch_deg (float) —step_size_B_deg (float)

For our rotations about X axis, we will use the following convention: —bracket_range_C_roll_deg (float) —step_size_C_deg (float)

Always apply the A rotation first. For each A position apply the full bracket of B positions. For each AB position apply the full bracket of C positions.

Name each position accordingly to its integer index within the location bracket.

i.e. “pose_x0-y0_A0-B2-C1”

Generating from Kalibr AprilGrid metadata

The AprilGrid metadata file is generated by the Kalibr tool.

{
  "description": "AprilGrid placement metadata for Blender. Kalibr origin is bottom-left corner of tag ID 0.",
  "units": "millimeters",
  "no_margin": true,
  "tag_size_mm": 20.0,
  "spacer_size_mm": 6.0,
  "tag_pitch_mm": 26.0,
  "grid_dimensions_mm": {
    "width": 624.0,
    "height": 624.0
  },
  "image_dimensions_mm": {
    "width": 630.0,
    "height": 630.0
  },
  "kalibr_origin_offset_from_image_bottom_left_mm": {
    "x": 6.0,
    "y": 6.0
  },
  "grid_top_right_from_kalibr_origin_mm": {
    "x": 618.0,
    "y": 618.0
  },
  "tags": [
    {
      "id": 0,
      "bottom_left_mm": {
        "x": 0.0,
        "y": 0.0
      },
      "top_right_mm": {
        "x": 20.0,
        "y": 20.0
      }
    },
    {
      "id": 1,
      "bottom_left_mm": {
        "x": 26.0,
        "y": 0.0
      },
      "top_right_mm": {
        "x": 46.0,
        "y": 20.0
      }
    },
    ...

generate_grid_scan_plan_from_aprilgrid_metadata(metadata_file: Path, z_height: float, ratio_of_target_coverage: float, density_of_poses_relative_fortynine: float, bracket_range_A_yaw_deg: float, step_size_A_deg: float, bracket_range_B_pitch_deg: float, step_size_B_deg: float, bracket_range_C_roll_deg: float, step_size_C_deg: float) -> ScanPlan

this does something sensible.

for example if our target is 1000mm and our ratio_of_target_coverage is 0.5, then we should generate a grid that covers 500mm of the target.

the default grid size is 7x7 poses (49 total). If density_of_poses_relative_fortynine is provided, it should be used to scale the number of poses generated. i.e. if density is 2.0, then we should generate a 14x14 grid (196 total poses).

all of bracket_range_A_yaw_deg: float, step_size_A_deg: float, bracket_range_B_pitch_deg: float, step_size_B_deg: float should default to 10 degrees with 5 degree step size

bracket_range_C_roll_deg: float, step_size_C_deg: float should default to 0 degrees with 5 degree step size