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For 3D and higher, only the matrix form is allowed." } ] }, { "__type": "Paragraph", "__tag": 4045, "children": [ { "__type": "Text", "__tag": 4046, "value": "In narrower transforms, such as the Euclidean (only rotation and translation) or Similarity (rotation, translation, and a global scale factor) transforms, it is possible to specify 3D transforms using implicit parameters also." } ] } ], "title": [], "level": 0, "target": null }, "Other Parameters": { "__type": "Section", "__tag": 4015, "children": [], "title": [], "level": 0, "target": null } }, "_ordered_sections": [ "Summary", "Extended Summary", "Parameters", "Returns", "Yields", "Receives", "Raises", "Warns", "Other Parameters", "Attributes", "Methods", "Notes", "Warnings" ], "item_file": "/dev/scikit-image/src/skimage/transform/_geometric.py", "item_line": 1327, "item_type": "ABCMeta", "aliases": [ "skimage.transform.AffineTransform" ], "example_section_data": { "__type": "Section", "__tag": 4015, "children": [ { "__type": "Code", "__tag": 4050, "value": "import numpy as np\nimport skimage as ski\n", "execution_status": "success" }, { "__type": "Text", "__tag": 4046, "value": "\nDefine a transform with an homogeneous transformation matrix:\n\n" }, { "__type": "Code", "__tag": 4050, "value": "tform = ski.transform.AffineTransform(np.diag([2., 3., 1.]))\ntform.params\n", "execution_status": "success" }, { "__type": "Text", "__tag": 4046, "value": "\nDefine a transform with parameters:\n\n" }, { "__type": "Code", "__tag": 4050, "value": "tform = ski.transform.AffineTransform(scale=4, rotation=0.2)\nnp.round(tform.params, 2)\n", "execution_status": "success" }, { "__type": "Text", "__tag": 4046, "value": "\nYou can estimate a transformation to map between source and destination\npoints:\n\n" }, { "__type": "Code", "__tag": 4050, "value": "src = np.array([[150, 150],\n [250, 100],\n [150, 200]])\ndst = np.array([[200, 200],\n [300, 150],\n [150, 400]])\ntform = ski.transform.AffineTransform.from_estimate(src, dst)\nnp.allclose(tform.params, [[ 0.5, -1. , 275. ],\n [ 1.5, 4. , -625. ],\n [ 0. , 0. , 1. ]])\n", "execution_status": "success" }, { "__type": "Text", "__tag": 4046, "value": "\nApply the transformation to some image data.\n\n" }, { "__type": "Code", "__tag": 4050, "value": "img = ski.data.astronaut()\nwarped = ski.transform.warp(img, inverse_map=tform.inverse)\n", "execution_status": "success" }, { "__type": "Text", "__tag": 4046, "value": "\nThe estimation can fail - for example, if all the input or output points\nare the same. If this happens, you will get a transform that is not\n\"truthy\" - meaning that ``bool(tform)`` is ``False``:\n\n" }, { "__type": "Code", "__tag": 4050, "value": "if tform:\n print(\"Estimation succeeded.\")\nbad_src = np.ones((3, 2))\nbad_tform = ski.transform.AffineTransform.from_estimate(\n bad_src, dst)\nif not bad_tform:\n print(\"Estimation failed.\")\n", "execution_status": "success" }, { "__type": "Text", "__tag": 4046, "value": "\nTrying to use this failed estimation transform result will give a suitable\nerror:\n\n" }, { "__type": "Code", "__tag": 4050, "value": "bad_tform.params # doctest: +IGNORE_EXCEPTION_DETAIL\n", "execution_status": "success" } ], "title": [], "level": 0, "target": null }, "see_also": [], "signature": { "__type": "SignatureNode", "__tag": 4029, "kind": "function", "parameters": [ { "__type": "SigParam", "__tag": 4030, "name": "matrix", "annotation": { "__type": "Empty", "__tag": 4031 }, "kind": "POSITIONAL_OR_KEYWORD", "default": "None" }, { "__type": "SigParam", "__tag": 4030, "name": "scale", "annotation": { "__type": "Empty", "__tag": 4031 }, "kind": "KEYWORD_ONLY", "default": "None" }, { "__type": "SigParam", "__tag": 4030, "name": "shear", "annotation": { "__type": "Empty", "__tag": 4031 }, "kind": "KEYWORD_ONLY", "default": "None" }, { "__type": "SigParam", "__tag": 4030, "name": "rotation", "annotation": { "__type": "Empty", "__tag": 4031 }, "kind": "KEYWORD_ONLY", "default": "None" }, { "__type": "SigParam", "__tag": 4030, "name": "translation", "annotation": { "__type": "Empty", "__tag": 4031 }, "kind": "KEYWORD_ONLY", "default": "None" }, { "__type": "SigParam", "__tag": 4030, "name": "dimensionality", "annotation": { "__type": "Empty", "__tag": 4031 }, "kind": "KEYWORD_ONLY", "default": "None" } ], "return_annotation": { "__type": "Empty", "__tag": 4031 }, "target_name": "AffineTransform" }, "references": [ ".. [1] Wikipedia, \"Affine transformation\",", " https://en.wikipedia.org/wiki/Affine_transformation#Image_transformation", ".. [2] Wikipedia, \"Shear mapping\",", " https://en.wikipedia.org/wiki/Shear_mapping" ], "qa": "skimage.transform._geometric:AffineTransform", "arbitrary": [], "local_refs": [ "dimensionality", "matrix", "params", "rotation", "scale", "shear", "translation" ] }