René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Sizes of different markers are not perceptually uniform","articleBody":"**Bug summary**\r\n\r\nMarkers of different types (\"o\", \"s\", \"*\" ...) do not visually appear to be of the same size when their marker size (e.g. ms=8) is equal (matplotlib 3.1.1).\r\n\r\n**Details**\r\n\r\nMatplotlib has a great selection of markers, but the relative sizes of these markers are not perceptually uniform, see\r\nhttps://matplotlib.org/3.1.1/api/markers_api.html\r\nor this example script:\r\n\r\n```\r\nfrom matplotlib import pyplot as plt\r\n\r\nplt.style.use(\"default\")\r\nimport numpy as np\r\n\r\nx = np.arange(4)\r\ny = np.ones(4)\r\n\r\nfor imarker, marker in enumerate(\"os*pv^\u003c\u003ePDdX\"):\r\n    plt.plot(x, y + 0.1 * imarker, marker=marker)\r\n\r\nplt.show()\r\n```\r\n\r\nThe square \"s\" and the diamond \"D\" appear larger than the other markers. The star \"*\" is the smallest, followed by the pentagon \"p\" and the plus \"P\".\r\n\r\n![image](https://user-images.githubusercontent.com/2631586/68998928-f1aef080-08b8-11ea-8633-805e604aa96b.png)\r\n\r\n**Expected outcome**\r\n\r\nMarkers should appear uniform in size. I think for the star this is very obviously not the case. The area of the star is much smaller than for the circle, and largest for the square and the diamond.\r\n\r\nNevertheless, I don't think an objective geometric criterion like area can be used to make them perceptually uniform in size. I think this needs to be hand-tuned by a human to take into account how humans perceive the relative size of objects.","author":{"url":"https://github.com/HDembinski","@type":"Person","name":"HDembinski"},"datePublished":"2019-11-16T20:41:02.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":24},"url":"https://github.com/15703/matplotlib/issues/15703"}