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identity with figure semantics or reading context enriched"},{"oldId":"b-74d11a0b5b3ad3c6082cc370","targetId":"b-74d11a0b5b3ad3c6082cc370","page":"reading-opening","operation":"move","beforeSHA256":"2b9ccef7e1220e2250cceff1abd8bdd736b42f8da5a223f26b029f44b962e807","afterSHA256":"2b9ccef7e1220e2250cceff1abd8bdd736b42f8da5a223f26b029f44b962e807","reason":"Same source body in authored semantic page"}],"blocks":[{"id":"b-efd7ccf3e7c1c182a4a629d7","type":"h1","scope":"bilinear-four-neighbors","url":"https://codingai-lec03.pages.dev/course/blocks/bilinear-four-neighbors.html#b-efd7ccf3e7c1c182a4a629d7","content":"# 四个邻点如何读出 2.5","sha256":"0252ea7aa9c804c5a8d8dbc7aaadbd1ab1075041f02760d818d4cfc0c25c0da6","chapter":{"id":"II","title":"区域、像素与实例"},"unit":{"id":"roi-alignment-and-evidence","title":"区域采样怎样保住几何对应？"},"page":{"id":"reading-opening","title":"四个邻点如何读出 2.5","number":1},"sectionTitle":"四个邻点如何读出 2.5","currentQuestion":"四个邻点如何读出 2.5","sourceSlides":[],"knowledgeBlock":null,"formulas":[],"previousBlock":null,"nextBlock":"b-277649253ac4a28f509be461","prerequisites":[{"id":"b-277649253ac4a28f509be461","url":"#b-277649253ac4a28f509be461","role":"problem-context"}],"relatedBlocks":[{"id":"b-7f710245d8cf2bfe73b9901a","url":"#b-7f710245d8cf2bfe73b9901a","relation":"figure-and-explanation"}]},{"id":"b-277649253ac4a28f509be461","type":"p","scope":"bilinear-four-neighbors","url":"https://codingai-lec03.pages.dev/course/blocks/bilinear-four-neighbors.html#b-277649253ac4a28f509be461","content":"对 0、2、4、6 四邻值，按横向 1/4、纵向 1/2 算出 2.5。两步插值与四项加权是同一运算。读完算例后，接着看[原论文的对照：对齐改善了哪些指标](/course/blocks/roi-align-paper-evidence.html)，区分“使用双线性插值”和“保持坐标对齐”的作用。","sha256":"185d6570689468f3c523e1d63cc5d2dd507c9b0ff60f2af36bd85b2834d7978e","chapter":{"id":"II","title":"区域、像素与实例"},"unit":{"id":"roi-alignment-and-evidence","title":"区域采样怎样保住几何对应？"},"page":{"id":"reading-opening","title":"四个邻点如何读出 2.5","number":1},"sectionTitle":"四个邻点如何读出 2.5","currentQuestion":"四个邻点如何读出 2.5","sourceSlides":[],"knowledgeBlock":null,"formulas":[],"previousBlock":"b-efd7ccf3e7c1c182a4a629d7","nextBlock":"b-a5ccb96f700937f8fe12e4f8","prerequisites":[{"id":"b-efd7ccf3e7c1c182a4a629d7","url":"#b-efd7ccf3e7c1c182a4a629d7","role":"section-title"}],"relatedBlocks":[{"id":"b-7f710245d8cf2bfe73b9901a","url":"#b-7f710245d8cf2bfe73b9901a","relation":"figure-and-explanation"}]},{"id":"b-a5ccb96f700937f8fe12e4f8","type":"p","scope":"bilinear-four-neighbors","url":"https://codingai-lec03.pages.dev/course/blocks/bilinear-four-neighbors.html#b-a5ccb96f700937f8fe12e4f8","content":"把左上、右上、左下、右下值依次记为 0、2、4、6。要读取的点相对左上角横向走了 α=1/4、纵向走了 β=1/2。上排插值为 $(1-α)0+α2=.5$，下排为 $(1-α)4+α6=4.5$，再纵向插值得 $(1-β).5+β4.5=2.5$。","sha256":"9068ee93532c027ce4a75a59639e005de9272ab4f6cedc3e1e4e0f6ab8dad0e6","chapter":{"id":"II","title":"区域、像素与实例"},"unit":{"id":"roi-alignment-and-evidence","title":"区域采样怎样保住几何对应？"},"page":{"id":"reading-opening","title":"四个邻点如何读出 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2.5"}],"previousBlock":"b-277649253ac4a28f509be461","nextBlock":"b-390baccceb95cec58054c8da","prerequisites":[{"id":"b-efd7ccf3e7c1c182a4a629d7","url":"#b-efd7ccf3e7c1c182a4a629d7","role":"section-title"},{"id":"b-277649253ac4a28f509be461","url":"#b-277649253ac4a28f509be461","role":"problem-context"}],"relatedBlocks":[{"id":"b-7f710245d8cf2bfe73b9901a","url":"#b-7f710245d8cf2bfe73b9901a","relation":"figure-and-explanation"}]},{"id":"b-390baccceb95cec58054c8da","type":"p","scope":"bilinear-four-neighbors","url":"https://codingai-lec03.pages.dev/course/blocks/bilinear-four-neighbors.html#b-390baccceb95cec58054c8da","content":"也可直接写四点加权和：","sha256":"6098132f38143db98713510c6df60aa2a55dfc48b17b0637c5e2592782dbb6c0","chapter":{"id":"II","title":"区域、像素与实例"},"unit":{"id":"roi-alignment-and-evidence","title":"区域采样怎样保住几何对应？"},"page":{"id":"reading-opening","title":"四个邻点如何读出 2.5","number":1},"sectionTitle":"四个邻点如何读出 2.5","currentQuestion":"四个邻点如何读出 2.5","sourceSlides":[],"knowledgeBlock":null,"formulas":[],"previousBlock":"b-a5ccb96f700937f8fe12e4f8","nextBlock":"b-4c0476cc5c72ab6958e865c5","prerequisites":[{"id":"b-efd7ccf3e7c1c182a4a629d7","url":"#b-efd7ccf3e7c1c182a4a629d7","role":"section-title"},{"id":"b-277649253ac4a28f509be461","url":"#b-277649253ac4a28f509be461","role":"problem-context"}],"relatedBlocks":[{"id":"b-7f710245d8cf2bfe73b9901a","url":"#b-7f710245d8cf2bfe73b9901a","relation":"figure-and-explanation"}]},{"id":"b-4c0476cc5c72ab6958e865c5","type":"p","scope":"bilinear-four-neighbors","url":"https://codingai-lec03.pages.dev/course/blocks/bilinear-four-neighbors.html#b-4c0476cc5c72ab6958e865c5","content":"$\nv=(1-α)(1-β)F_{00}+α(1-β)F_{10}+(1-α)βF_{01}+αβF_{11}.\n$","sha256":"e08caebafdde342be57aa6b66bdec78b97e37eaf0745834abac6b5dabd48f342","chapter":{"id":"II","title":"区域、像素与实例"},"unit":{"id":"roi-alignment-and-evidence","title":"区域采样怎样保住几何对应？"},"page":{"id":"reading-opening","title":"四个邻点如何读出 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1/2。这些比例直接来自几何，而不是学出来的四个自由参数。","sha256":"7cb60f9af73cf3da129cce8fba643e88e045cb9f8723c215c7a46c9c821c4b96","chapter":{"id":"II","title":"区域、像素与实例"},"unit":{"id":"roi-alignment-and-evidence","title":"区域采样怎样保住几何对应？"},"page":{"id":"reading-opening","title":"四个邻点如何读出 2.5","number":1},"sectionTitle":"四个邻点如何读出 2.5","currentQuestion":"四个邻点如何读出 2.5","sourceSlides":[],"knowledgeBlock":null,"formulas":[{"latex":"0+2/8+12/8+6/8=2.5","definitionContext":"四个邻点如何读出 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2.5","sourceSlides":[],"knowledgeBlock":null,"formulas":[],"previousBlock":"b-b1acdda3d2f11c9864e4f8fc","nextBlock":"b-aaf8ab3491c61d247312b466","prerequisites":[{"id":"b-efd7ccf3e7c1c182a4a629d7","url":"#b-efd7ccf3e7c1c182a4a629d7","role":"section-title"},{"id":"b-277649253ac4a28f509be461","url":"#b-277649253ac4a28f509be461","role":"problem-context"}],"relatedBlocks":[{"id":"b-7f710245d8cf2bfe73b9901a","url":"#b-7f710245d8cf2bfe73b9901a","relation":"figure-and-explanation"}]},{"id":"b-aaf8ab3491c61d247312b466","type":"p","scope":"bilinear-four-neighbors","url":"https://codingai-lec03.pages.dev/course/blocks/bilinear-four-neighbors.html#b-aaf8ab3491c61d247312b466","content":"读完算例后，接着看[原论文的对照：对齐改善了哪些指标](/course/blocks/roi-align-paper-evidence.html)，区分“使用双线性插值”和“保持坐标对齐”的作用。","sha256":"53a805f92a552538c0667b62945f85ee07625d6afae225bf981b2bd38b85b9d5","chapter":{"id":"II","title":"区域、像素与实例"},"unit":{"id":"roi-alignment-and-evidence","title":"区域采样怎样保住几何对应？"},"page":{"id":"reading-opening","title":"四个邻点如何读出 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还要组织分格、多个采样点与汇总。\n\n四点值、四项权重与两步插值都对应同一采样位置。 查看对应图解状态\n\n- F = [[0,2],[4,6]]；x 向右，y 向下\n- 0\n- 2\n- 4\n- 6\n- (.25, .5)\n- x\n- y\n- 上行：¾×0 + ¼×2 = 0.5\n- 下行：¾×4 + ¼×6 = 4.5\n- 再取两行中间值\n- ½×0.5 + ½×4.5 = 2.5\n- 四邻点权重：⅜，⅛，⅜，⅛\n- 权重和 = 1；结果 = 2.5\n- 一个连续采样点的双线性算例；完整 RoIAlign 还要组织分格、多个采样点与汇总。四点值、四项权重与两步插值都对应同一采样位置。 [查看对应图解状态](/#/l3-r2-p42/1)[查看完整图解](/#/l3-r2-p42/1)","sha256":"282724d73b876c699a4f926bc78806c3c719b86eb892afb42474e6ccfac640ac","chapter":{"id":"II","title":"区域、像素与实例"},"unit":{"id":"roi-alignment-and-evidence","title":"区域采样怎样保住几何对应？"},"page":{"id":"reading-opening","title":"四个邻点如何读出 2.5","number":1},"sectionTitle":"四个邻点如何读出 2.5","currentQuestion":"四个邻点如何读出 2.5","sourceSlides":[],"knowledgeBlock":null,"formulas":[],"figure":{"caption":"四点值、四项权重与两步插值都对应同一采样位置。 查看对应图解状态","labels":["F = [[0,2],[4,6]]；x 向右，y 向下","0","2","4","6","(.25, .5)","x","y","上行：¾×0 + ¼×2 = 0.5","下行：¾×4 + ¼×6 = 4.5","再取两行中间值","½×0.5 + ½×4.5 = 2.5","四邻点权重：⅜，⅛，⅜，⅛","权重和 = 1；结果 = 2.5","一个连续采样点的双线性算例；完整 RoIAlign 还要组织分格、多个采样点与汇总。"],"description":"四点值、四项权重与两步插值都对应同一采样位置。 查看对应图解状态F = [[0,2],[4,6]]；x 向右，y 向下0246(.25, .5)xy上行：¾×0 + ¼×2 = 0.5下行：¾×4 + ¼×6 = 4.5再取两行中间值½×0.5 + ½×4.5 = 2.5四邻点权重：⅜，⅛，⅜，⅛权重和 = 1；结果 = 2.5一个连续采样点的双线性算例；完整 RoIAlign 还要组织分格、多个采样点与汇总。","evidenceIdentity":"四点值、四项权重与两步插值都对应同一采样位置。 查看对应图解状态","images":[]},"previousBlock":"b-aaf8ab3491c61d247312b466","nextBlock":"b-74d11a0b5b3ad3c6082cc370","prerequisites":[{"id":"b-efd7ccf3e7c1c182a4a629d7","url":"#b-efd7ccf3e7c1c182a4a629d7","role":"section-title"},{"id":"b-277649253ac4a28f509be461","url":"#b-277649253ac4a28f509be461","role":"problem-context"}],"relatedBlocks":[]},{"id":"b-74d11a0b5b3ad3c6082cc370","type":"h2","scope":"bilinear-four-neighbors","url":"https://codingai-lec03.pages.dev/course/blocks/bilinear-four-neighbors.html#b-74d11a0b5b3ad3c6082cc370","content":"## 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