{
  "id": 125278,
  "title": "Cars facing away from camera",
  "url": "/competitions/pku-autonomous-driving/discussion/125278",
  "author_name": "",
  "post_date": "2020-01-09T17:19:54.285557400Z",
  "votes": 1,
  "comment_count": 1,
  "views": 0,
  "content": "<p>When cars face away from camera, pitch can be 3.1/-3.1, which is just crossing the pi/-pi line. This seems to disturb the accuracy a lot, since a small change across the line adds much more to the loss. Any way to tackle this?</p>",
  "messages": [
    {
      "id": "714714",
      "postDate": "01/09/2020 17:19:54",
      "content": "<p>When cars face away from camera, pitch can be 3.1/-3.1, which is just crossing the pi/-pi line. This seems to disturb the accuracy a lot, since a small change across the line adds much more to the loss. Any way to tackle this?</p>",
      "rawMarkdown": "When cars face away from camera, pitch can be 3.1/-3.1, which is just crossing the pi/-pi line. This seems to disturb the accuracy a lot, since a small change across the line adds much more to the loss. Any way to tackle this?",
      "votes": null
    },
    {
      "id": "714777",
      "postDate": "01/09/2020 18:26:33",
      "content": "<p>Instead of regressing the raw angle value decompose it into its sin and cosine. cos(±π) = -1 and sin(π) = 0. For your example, the cosines will be equal and the difference between the sines will be small. Later you can recover the angle using tan(x) = sin(x) / cos(x).</p>",
      "rawMarkdown": "Instead of regressing the raw angle value decompose it into its sin and cosine. cos(±π) = -1 and sin(π) = 0. For your example, the cosines will be equal and the difference between the sines will be small. Later you can recover the angle using tan(x) = sin(x) / cos(x).",
      "votes": null
    }
  ],
  "comments": [
    {
      "id": 714777,
      "author_name": "selameab",
      "author_url": "",
      "post_date": "01/09/2020 18:26:33",
      "content": "<p>Instead of regressing the raw angle value decompose it into its sin and cosine. cos(±π) = -1 and sin(π) = 0. For your example, the cosines will be equal and the difference between the sines will be small. Later you can recover the angle using tan(x) = sin(x) / cos(x).</p>",
      "votes": null,
      "replies": []
    }
  ],
  "raw_markdown_by_id": {
    "714714": "When cars face away from camera, pitch can be 3.1/-3.1, which is just crossing the pi/-pi line. This seems to disturb the accuracy a lot, since a small change across the line adds much more to the loss. Any way to tackle this?",
    "714777": "Instead of regressing the raw angle value decompose it into its sin and cosine. cos(±π) = -1 and sin(π) = 0. For your example, the cosines will be equal and the difference between the sines will be small. Later you can recover the angle using tan(x) = sin(x) / cos(x)."
  },
  "source": "meta"
}