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diff --git a/docs/user_guide/aruco_marker_pipeline/aruco_markers_description.md b/docs/user_guide/aruco_marker_pipeline/aruco_markers_description.md new file mode 100644 index 0000000..66a0581 --- /dev/null +++ b/docs/user_guide/aruco_marker_pipeline/aruco_markers_description.md @@ -0,0 +1,120 @@ +Set up ArUco markers +==================== + +First of all, ArUco markers needs to be printed and placed into the scene. + +Here is an example scene where markers are surrounding a workspace with two screens, a control panel and a window. + + + +## Print ArUco markers from an ArUco dictionary + +ArUco markers always belongs to a set of markers called ArUco markers dictionary. + + + +Many ArUco dictionaries exist with properties concerning the format, the number of markers or the difference between each markers to avoid error in tracking. + +Here is the documention [about ArUco markers dictionaries](https://docs.opencv.org/3.4/d9/d6a/group__aruco.html#gac84398a9ed9dd01306592dd616c2c975). + +The creation of [ArUcoMarkers](../../argaze.md/#argaze.ArUcoMarkers.ArUcoMarker) pictures from a dictionary is illustrated in the code below: + +```python +from argaze.ArUcoMarkers import ArUcoMarkersDictionary + +# Create a dictionary of specific April tags +aruco_dictionary = ArUcoMarkersDictionary.ArUcoMarkersDictionary('DICT_APRILTAG_16h5') + +# Export marker n°5 as 3.5 cm picture with 300 dpi resolution +aruco_dictionary.create_marker(5, 3.5).save('./markers/', 300) + +# Export all dictionary markers as 3.5 cm pictures with 300 dpi resolution +aruco_dictionary.save('./markers/', 3.5, 300) +``` + +!!! note + There is **A4_DICT_APRILTAG_16h5_5cm_0-7.pdf** file located in *./src/argaze/ArUcoMarkers/utils/* folder ready to be printed on A4 paper sheet. + +Let's print some of them before to go further. + +!!! warning + Print markers with a blank zone around them to help in their detection. + +## Describe ArUco markers place + +Once [ArUcoMarkers](../../argaze.md/#argaze.ArUcoMarkers.ArUcoMarker) pictures are placed into a scene it is possible to describe their 3D places into a file. + + + +Where ever the origin point is, all markers places need to be described in a [right-handed 3D axis](https://robotacademy.net.au/lesson/right-handed-3d-coordinate-frame/) where: + +* +X is pointing to the right, +* +Y is pointing to the top, +* +Z is pointing to the backward. + +!!! warning + All ArUco markers spatial values must be given in **centimeters**. + +### Edit OBJ file description + +OBJ file format could be exported from most 3D editors. + +``` obj +o DICT_APRILTAG_16h5#0_Marker +v 15.000000 0.378741 0.330527 +v 20.000000 0.378741 0.330527 +v 15.000000 5.120359 -1.255996 +v 20.000000 5.120359 -1.255996 +f 1 2 4 3 +o DICT_APRILTAG_16h5#1_Marker +v 43.500000 31.428055 18.333317 +v 48.500000 31.428055 18.333317 +v 43.500000 36.428055 18.333317 +v 48.500000 36.428055 18.333317 +f 5 6 8 7 +o DICT_APRILTAG_16h5#2_Marker +v 38.500000 2.678055 5.498381 +v 43.500000 2.678055 5.498381 +v 38.500000 5.178055 1.168253 +v 43.500000 5.178055 1.168253 +f 9 10 12 11 +``` + +Here are common OBJ file features needed to describe ArUco markers places: + +* Object lines (starting with *o* key) indicate markers dictionary and id by following this format: **DICTIONARY**#**ID**\_Marker. +* Vertice lines (starting with *v* key) indicate markers corners. The marker size will be automatically deducted from the geometry. +* Face (starting with *f* key) link vertices and normals indexes together. + +!!! warning + Markers have to belong to the same dictionary. + +!!! note + Markers can have different size. + +### Edit JSON file description + +JSON file format allows to describe markers places using translation and euler angle rotation vectors. + +``` json +{ + "dictionary": "DICT_APRILTAG_16h5", + "places": { + "0": { + "translation": [17.5, 2.75, -0.5], + "rotation": [-18.5, 0, 0], + "size": 5 + }, + "1": { + "translation": [46, 34, 18.333], + "rotation": [0, 70, 0], + "size": 5 + }, + "2": { + "translation": [41, 4, 3.333], + "rotation": [-60, 0, 0], + "size": 5 + } + } +} +``` |