{
  "id": 232245,
  "title": "What are Y and Z... and why isn't one of them almost constant?",
  "url": "/competitions/pku-autonomous-driving/discussion/232245",
  "author_name": "",
  "post_date": "2021-04-12T19:42:28.542525900Z",
  "votes": 1,
  "comment_count": 1,
  "views": 0,
  "content": "<p>I'd like to use this dataset just to estimate the distance to other cars.</p>\n<pre><code>distance = np.sqrt(x**2 + y**2)\n\nor even better, distance = np.sqrt(x**2 + y**2 + z**2)\n</code></pre>\n<p>I was expecting the axis Y having info regarding the distance.</p>\n<p>And axis Z having more or less the same constant value, since all these cars are in the same horizontal plane.</p>\n<p>I'm not very sure how is the reference coordinates axis, perhaps I'm confusing axis Z with Y.<br>\nBut the fact is that both increases with distance, and I was expecting one of them to be constant.</p>\n<p>Aren't X, Y, Z Cartesian coordinates?  what measure unit is used for these coordinates?</p>",
  "messages": [
    {
      "id": "1271698",
      "postDate": "04/12/2021 19:42:28",
      "content": "<p>I'd like to use this dataset just to estimate the distance to other cars.</p>\n<pre><code>distance = np.sqrt(x**2 + y**2)\n\nor even better, distance = np.sqrt(x**2 + y**2 + z**2)\n</code></pre>\n<p>I was expecting the axis Y having info regarding the distance.</p>\n<p>And axis Z having more or less the same constant value, since all these cars are in the same horizontal plane.</p>\n<p>I'm not very sure how is the reference coordinates axis, perhaps I'm confusing axis Z with Y.<br>\nBut the fact is that both increases with distance, and I was expecting one of them to be constant.</p>\n<p>Aren't X, Y, Z Cartesian coordinates?  what measure unit is used for these coordinates?</p>",
      "rawMarkdown": "I'd like to use this dataset just to estimate the distance to other cars.\n\n```\ndistance = np.sqrt(x**2 + y**2)\n\nor even better, distance = np.sqrt(x**2 + y**2 + z**2)\n```\n\nI was expecting the axis Y having info regarding the distance.\n\nAnd axis Z having more or less the same constant value, since all these cars are in the same horizontal plane.\n\nI'm not very sure how is the reference coordinates axis, perhaps I'm confusing axis Z with Y.\nBut the fact is that both increases with distance, and I was expecting one of them to be constant.\n\nAren't X, Y, Z Cartesian coordinates?  what measure unit is used for these coordinates?",
      "votes": null
    },
    {
      "id": "1323325",
      "postDate": "05/26/2021 06:50:44",
      "content": "<p>This is a 2 dimensional picture and thus there is no 'Z' direction. But if you're trying to get the (x,y,z) coordinates of the cars from the 2D image , then nothing would be constant. As in the 3D space all the objects have different , a well trained model will try and do the same for its predictions using the image.</p>",
      "rawMarkdown": "This is a 2 dimensional picture and thus there is no 'Z' direction. But if you're trying to get the (x,y,z) coordinates of the cars from the 2D image , then nothing would be constant. As in the 3D space all the objects have different , a well trained model will try and do the same for its predictions using the image.",
      "votes": null
    }
  ],
  "comments": [
    {
      "id": 1323325,
      "author_name": "puranjaymishra",
      "author_url": "",
      "post_date": "05/26/2021 06:50:44",
      "content": "<p>This is a 2 dimensional picture and thus there is no 'Z' direction. But if you're trying to get the (x,y,z) coordinates of the cars from the 2D image , then nothing would be constant. As in the 3D space all the objects have different , a well trained model will try and do the same for its predictions using the image.</p>",
      "votes": null,
      "replies": []
    }
  ],
  "raw_markdown_by_id": {
    "1271698": "I'd like to use this dataset just to estimate the distance to other cars.\n\n```\ndistance = np.sqrt(x**2 + y**2)\n\nor even better, distance = np.sqrt(x**2 + y**2 + z**2)\n```\n\nI was expecting the axis Y having info regarding the distance.\n\nAnd axis Z having more or less the same constant value, since all these cars are in the same horizontal plane.\n\nI'm not very sure how is the reference coordinates axis, perhaps I'm confusing axis Z with Y.\nBut the fact is that both increases with distance, and I was expecting one of them to be constant.\n\nAren't X, Y, Z Cartesian coordinates?  what measure unit is used for these coordinates?",
    "1323325": "This is a 2 dimensional picture and thus there is no 'Z' direction. But if you're trying to get the (x,y,z) coordinates of the cars from the 2D image , then nothing would be constant. As in the 3D space all the objects have different , a well trained model will try and do the same for its predictions using the image."
  },
  "source": "meta"
}