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+Describe 3D AOI
+===============
+
+Now [scene pose is estimated](aruco_markers_description.md) thanks to ArUco markers description, [areas of interest (AOI)](../../argaze.md/#argaze.AreaOfInterest.AOIFeatures.AreaOfInterest) need to be described into the same 3D referential.
+
+In the example scene, the screen and the sheet are considered as areas of interest.
+
+![3D AOI description](../../img/aoi_3d_description.png)
+
+All AOI need to be described from same origin than markers 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 AOI spatial values must be given in **centimeters**.
+
+### Edit OBJ file description
+
+OBJ file format could be exported from most 3D editors.
+
+``` obj
+o Sheet
+v 14.200000 -3.000000 28.350000
+v 35.200000 -3.000000 28.350000
+v 14.200000 -3.000000 -1.35
+v 35.200000 -3.000000 -1.35
+f 1 2 4 3
+o Screen
+v 2.750000 2.900000 -0.500000
+v 49.250000 2.900000 -0.500000
+v 2.750000 29.100000 -0.500000
+v 49.250000 29.100000 -0.500000
+f 5 6 8 7
+```
+
+Here are common OBJ file features needed to describe AOI:  
+
+* Object lines (starting with *o* key) indicate AOI name.
+* Vertice lines (starting with *v* key) indicate AOI vertices.
+* Face (starting with *f* key) link vertices together.
+
+### Edit JSON file description
+
+JSON file format allows to describe AOI vertices.
+
+``` json
+{
+    "Sheet": [[14.2, -3, 28.35], [35.2, -3, 28.35], [14.2, -3, -1.35], [35.2, -3, -1.35]],
+    "Screen": [[2.75, 2.9, -0.5], [49.25, 2.9, -0.5], [2.75, 29.1, -0.5], [49.25, 29.1, -0.5]]
+}
+```