transformation

I'm trying to compare 2 images that are taken from a digital camera. Since there may be movement on the camera, I want to first make the pictures "match" and then compare (using some distant function). To match them, I'm thinking about cropping the second picture and using SIFT to find it inside the first picture... it will probably have a small difference on scale/translation/rotation so then I'd need to find the transformation matrix that converts image 1 to image 2 (based on points found by SIFT) any ideas on how to do that (or I guess that's a common problem that may have some opensource

I'm comparing two different linear math libraries for 3D graphics using matrices. Here are two similar Translate functions from the two libraries: static Matrix4<T> Translate(T x, T y, T z) { Matrix4 m; m.x.x = 1; m.x.y = 0; m.x.z = 0; m.x.w = 0; m.y.x = 0; m.y.y = 1; m.y.z = 0; m.y.w = 0; m.z.x = 0; m.z.y = 0; m.z.z = 1; m.z.w = 0; m.w.x = x; m.w.y = y; m.w.z = z; m.w.w = 1; return m; } (c++ library from SO user prideout) static inline void mat4x4_translate(mat4x4 T, float x, float y, float z) { mat4x4_identity(T); T[3][0] = x; T[3][1] = y; T[3][2] = z; } (linmath c library from SO user

I want to draw an image using a HTML5 canvas, translate the image and then change the image but keep the transformations I've made. Is this possible? Here's some pseudo-code to illustrate my problem: // initially draw an image and translate it var context = canvas.getContext("2d"); context.putImageData(someData, 0, 0); context.translate(200, 10); // then later somewhere else in code // this should be drawn @ 200/10 var context = canvas.getContext("2d"); context.putImageData(someOtherData, ?, ?); I thought this would be possible by some save/restore calls but I did not succeed yet, so how can I

Question is simple so, no codes! If someone knows Box2D and SDL2, then, please tell me how to wrap SDL_Rect with b2body. Ofcourse, it requires to know the conversion of metre to pixel and vice versa. This is because Box2D measures distance in metres. Can you give me a simple expression or function to convert metres(of Box2D) to pixels or pixels to metres(of Box2D)? Can you give me a simple expression or function to convert metres(of Box2D) to pixels or pixels to metres(of Box2D)? Unfortunately, this isn't as simple as it sounds, for us. Because, if your game is on worms, then your game world

Please keep in mind I'm new to scala. This is the example I am trying to follow: https://spark.apache.org/docs/1.5.1/ml-ann.html It uses this dataset: https://github.com/apache/spark/blob/master/data/mllib/sample_multiclass_classification_data.txt I have prepared my .csv using the code below to get a data frame for classification in Scala. //imports for ML import org.apache.spark.ml.classification.MultilayerPerceptronClassifier import org.apache.spark.ml.evaluation.MulticlassClassificationEvaluator import org.apache.spark.mllib.util.MLUtils import org.apache.spark.sql.Row //imports for