points

问题 I have text file with point cloud data. This document contains six columns: x,y,z coordinates of points and nx,ny, nz - normal vector coordinate i.e., -2.27535 2.33442 12.8694 0.492013 -0.866115 -0.0881364 Could anyone tell me how can I remove hidden points (which are located in the back surface or are not visible in the view) using normal vector? I'm using Matlab.I will appreciate every helpful tip. 回答1: You probably refer to back face culling: you can determine, using dot product between

问题 This question already has an answer here : How to efficiently get 10% of random numbers, then 10% of remaining 90 etc untill all points allocated (1 answer) Closed 6 years ago . I have a set of points xyz8, I want to randomly get 10% of points. Then I want to randomly get 10% of the remaining 90% Then I want to randomly get 10% of the remaining 70% etc until all points done How can I go about doing this? Any advice is hugely appreciated 回答1: something like: import random l = [1,2,3,4] random

问题 I have a set of 2D points (not ordered) forming a closed contour, and I would like to resample them to 14 equally spaced points. It is a contour of a kidney on an image. Any ideas? 回答1: One intuitive approach (IMO) is to create an independent variable for both x and y . Base it on arc length, and interpolate on it. % close the contour, temporarily xc = [x(:); x(1)]; yc = [y(:); y(1)]; % current spacing may not be equally spaced dx = diff(xc); dy = diff(yc); % distances between consecutive

问题 I have a set of 2D points (not ordered) forming a closed contour, and I would like to resample them to 14 equally spaced points. It is a contour of a kidney on an image. Any ideas? 回答1: One intuitive approach (IMO) is to create an independent variable for both x and y . Base it on arc length, and interpolate on it. % close the contour, temporarily xc = [x(:); x(1)]; yc = [y(:); y(1)]; % current spacing may not be equally spaced dx = diff(xc); dy = diff(yc); % distances between consecutive

问题 In Cocos2D I am creating my CCSprites with anchor points of (0,1) which is similar to the way UIKit does it. Anyway, I am trying to change the anchor point in Box2D, is this possible? If so how would I do it with an anchor point of (0,1)? Thanks! 回答1: Box2D bodies don't have an anchor point. The anchorPoint is an offset of a node's texture relative to the node's position. Box2D bodies don't have a texture, hence no anchor point. Generally speaking you're going to make a lot of things more

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 6 years ago . I have two points, lets say x1,y1 and x2,y2. and i have one more point x3,y3, here is the question, i need to check is x3,y3 coordinate occurs in the line between x1,y1 and x2,y2 or not occurs in javascript. Thanks in advance. 回答1: Try this: var point_a = [0, 0]; var point_b = [100, 200]; var coord = [50, 100];

问题 I need to find the 2 points of the visual horizon , of a curved face. I have: XYZ of the 4 corner points XYZ of the 2 curved edge bezier points And I need to calculate either: XY of the horizon points XYZ of the horizon points 回答1: First off you have to convert your 3D beziers to 2D. If I remember right it's sufficient to project the curves just like you project 3D points for rendering. Afterwards you have to find the extrema of the curves. A small HowTo: Convert your bezier-curve from bezier

问题 I have a text file full of points. They are separated on each line by a comma-limited (x,y) pair. eg. -43.1234,40.1234\n -43.1244,40.1244\n etc. I now need to create a polygon around each of these points. The polygon has to have a 15 kilometer buffer from the point. I don't have access to ArcGIS or any other GIS that provides this functionality for me so at this point, I am wondering if anyone has the math that will help me get started? 回答1: You want to use GDAL/OGR/OSR, which does

问题 I have a N number of random points (in this case 20), with a X,Y and Z constrains. How can I create ANY (preferably closed) shape (using Three.js library) , given and starting only from N random points. There are probably many variants, please share yours. var program = new Program(reset,step) program.add('g',false) function reset() { scene.clear() scene.add(new THREE.GridHelper(100,1)) } function step() { } program.startup() var numpoints = 20; var dots = []; //If you want to use for other

问题 I am having some troubles trying to connect separate points in my picture (see below). Right now, the code I have is as follows: first_time = resulting_coords[0:40] for i in range(len(first_time)): if(i < (len(first_time))-1): cv2.line(copy_test_image[0], (resulting_coords[i,0],resulting_coords[i,1]), (resulting_coords[i+1,0],resulting_coords[i+1,1]), (0,0,225), 2) elif(i>=(len(first_time))-1): # print(i) cv2.line(copy_test_image[0], (resulting_coords[i,0],resulting_coords[i,1]), (resulting