From 3f8404d53e3b385d98d0329ce87aea5b009fca89 Mon Sep 17 00:00:00 2001 From: Lynx Date: Sun, 11 Aug 2024 21:08:05 +0200 Subject: [PATCH] Add code and explaination to blog post --- Readme.md | 4 +++ blog/blog.md | 78 ++++++++++++++++++++++++++++++++++++++++++++++++---- 2 files changed, 77 insertions(+), 5 deletions(-) diff --git a/Readme.md b/Readme.md index 081d1de..9f193af 100644 --- a/Readme.md +++ b/Readme.md @@ -31,3 +31,7 @@ - The test images were generated using - https://moonlit.technology/cqql/frost_patterns + +# Build Blog + +- pandoc --standalone blog.md -o shape_matching.html --metadata title="Shape Matching" diff --git a/blog/blog.md b/blog/blog.md index 38f0f99..79d61b2 100644 --- a/blog/blog.md +++ b/blog/blog.md @@ -1,6 +1,6 @@ # Acknowledgements -I blame [cqql](https://tech.lgbt/@cqql) for this existing. +I blame [cqql](https://cqql.site) for this existing. # Disclaimer @@ -9,10 +9,10 @@ I largely know nothing about this topic and everything you see here is knowledge # The Idea -![hi! :neocat_floof:\nI'm looking for help with programmatic shape retrieval. I need to rank a couple million shapes by how similar each is to a shape given as input. \ndo you know anything about this or anyone that could help me? I'd really appreciate boosts! :blobcatheartR:](Idea.png) +![hi! :neocat_floof:\nI'm looking for help with programmatic shape retrieval. I need to rank a couple million shapes by how similar each is to a shape given as input. \ndo you know anything about this or anyone that could help me? I'd really appreciate boosts! :blobcatheartR:](Idea.png) This is the post that threw me down this rabbit hole and started it all. -After doing a bit of searching around, for ways to maybe solve this problem I stumbled on opencv, which also happens to have a python port. Perfect for quickly hacking something together. +After doing a bit of searching around, for ways to maybe solve this problem I stumbled on OpenCV, which also happens to have a python port. Perfect for quickly hacking something together. # The Process @@ -22,6 +22,19 @@ First I imported the image as grayscale and let OpenCV find the contours for me. Which we can trace to form the complete outline as seen here: ![Contours](contours.png) +Actually Implementing this was as simple as +```py +def GetContoursFromFiles(): + cnt = [] + for i in range (0, MAX, 1): + img = cv2.imread(str(i)+'.png',0) + ret, thresh1 = cv2.threshold(img, GrayscaleThreshhold, 255,cv2.THRESH_BINARY_INV) + contours,hierarchy = cv2.findContours(thresh1,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE) + print("Number of Shapes detected in Image "+str(i)+":",len(contours)) + cnt.append(contours[0]) + return cnt +``` + Next, I had OpenCV compare the different outlines with each other, which I used to build a NxN Matrix of weights. (I love when libraries already do everything for me, especially all the math I wouldn't even know where to start with learning it). Then I just had to pretty print the matrix and that could be considered Task Complete: @@ -36,6 +49,54 @@ So that's exactly what I did. I stitched together all the source images to form But the result was well worth the effort: ![Graphical Matrix](Matrix.png) +So, what actually took all the effort? +This: + +```py +def CreateMatchingColorMatrix(mat): + + im_res = cv2.imread(str(0)+'.png',cv2.IMREAD_COLOR) + height, width, channels = im_res.shape + # (Coordinate 0/0) Color (white) + im_temp = np.full((height, width, 3), 255, np.uint8) + + norm = matplotlib.colors.Normalize(vmin=0.0, vmax=NormUpperBound) + # Build Topmost row (just iterate through all images and concat them sequentially) + for i in range(0, MAX, 1): + img = cv2.imread(str(i)+'.png',cv2.IMREAD_COLOR) + imgg = cv2.imread(str(i)+'.png',0) + ret, thresh1 = cv2.threshold(imgg, GrayscaleThreshhold, 255,cv2.THRESH_BINARY_INV) + # find the contours in the binary image + contours,hierarchy = cv2.findContours(thresh1,cv2.RETR_TREE,cv2.CHAIN_APPROX_NONE) + img = cv2.drawContours(img,contours[0] , -1, (255, 0,0), 3) + im_temp = cv2.hconcat([im_temp, img]) + # This top row is now our first row + im_res = im_temp + # Build The matrix row by row + for i in range(0, MAX, 1): + im_temp = cv2.imread(str(i)+'.png',cv2.IMREAD_COLOR) + img = np.full((height, width, 3), 255, np.uint8) + img[:] = (0, 0, 255) + # Individual row here, current sequential image gets chosen above, so here, we can do square coloring + for j in range(0, MAX, 1): + cmap = matplotlib.cm.get_cmap('brg_r') + cmap.set_over((0.0,0.0,0.0)) + # Gets current weight, normalises it, looks it up in color map, converts it to full scale, colors + img[:] = NtoF(cmap(norm(mat[i*MAX+j]))[:-1]) + # build up row + im_temp = cv2.hconcat([im_temp, img]) + #build up matrix + im_res = cv2.vconcat([im_res, im_temp]) + DebugDrawImage(im_res) +``` + +That's because I'm assembling the Matrix piece by piece and since I was learning as I went, I incrementally built it in such a way, that one part completely worked before moving on to the rest. +Specifically, I first tried to build the row and column headers, by filling all the other spaces with a dummy image 0.png. Then I had to figure out how to color them white. Afterwards, I tried to color code them, at which point I pulled in matplotlib for the colormaps. But because it uses different value ranged, I needed to do a bit of back and forth conversion, which led to this fun line which does all the heavy lifting for the coloring right here: +```py +# Gets current weight, normalises it, looks it up in color map, converts it to full scale, colors +img[:] = NtoF(cmap(norm(mat[i*MAX+j]))[:-1]) +``` + # Rotation @@ -56,7 +117,7 @@ To Demonstrate, here we have 45° Rotations of the same object, performed with d ![Rotation similarities displayed Graphically](rot2.png) ![Rotation similarities displayed using weights](rot2w.png) -The second algorithm seemed to perform more consistantly when using 45° rotations. Sadly, it completely failed with 22.5° rotations (which may be something I could fix, but I've already spent enough time on a "let's just do 10-15 minutes of research" project.) +The second algorithm seemed to perform more consistently when using 45° rotations. Sadly, it completely failed with 22.5° rotations (which may be something I could fix, but I've already spent enough time on a "let's just do 10-15 minutes of research" project.) # Why write this post in the first place? @@ -76,4 +137,11 @@ I used the Frost Pattern Generator written by cqql for my sample images, as they Now, keep in mind, this was quickly hacked together while I was learning how to even do this thing. With this disclaimer, the code can be found here: [https://moonlit.technology/NixLynx/shape_matching](https://moonlit.technology/NixLynx/shape_matching) -(Make sure to follow the license) +(Make sure to follow the license :3) + + +``` {=html} + +``` \ No newline at end of file