jlouthan / perspective-transform Goto Github PK

I could not get this to give correct results.

Instead, this library worked well for me: https://www.npmjs.com/package/simple-homography

Note there's a mistake in the README, it should be:

let B = math.multiply(homography, A).toArray()

I have a homographic transform matrix (3X3) and I want to transform a div from its default position according to this matrix.

Is it possible to that with this library?
It looks like perspT.coeffs is a getter.

Hi,
Is it possible that we can use this library for an nth number of points?
eg: - [158, 64, 494, 69, 495, 404, 158, 404, 495, 404, 495, 404 ...n]

Hello,

What is the license of these project ? I need to know the license to be able to use this lib in my own project.

Best regards,

var PerspT = require('perspective-transform');
const src = [ 0, 0, 0, 1024, 1024, 0, 1024, 1024 ];
const dest = [ 512, 171, 512, 853, 512, 0, 512, 1024 ];
var perspT = PerspT(src, dest);

When I try to map to a quadrilateral where all the x coordinates are the same, I get the following error:

TypeError: Cannot read property '3' of undefined
    at Object.inv (C:\Users\Ryan\Documents\Code\js_playground\node_modules\perspective-transform\dist\perspective-transform.js:98:17)
    at getNormalizationCoefficients (C:\Users\Ryan\Documents\Code\js_playground\node_modules\perspective-transform\dist\perspective-transform.js:224:22)
    at PerspT (C:\Users\Ryan\Documents\Code\js_playground\node_modules\perspective-transform\dist\perspective-transform.js:248:20)
    at PerspT (C:\Users\Ryan\Documents\Code\js_playground\node_modules\perspective-transform\dist\perspective-transform.js:242:11)
    at Object.<anonymous> (C:\Users\Ryan\Documents\Code\js_playground\js.js:5:14)
    at Module._compile (module.js:571:32)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)

I poked around in the code a bit to try to come up with a nice solution, but the best I could get was throwing in a check like:

if(dstPts[0] === dstPts[2] && dstPts[0] === dstPts[4] && dstPts[0] === dstPts[6]){
    this.coeffs = [0, 0, dstPts[0], 0, 1, 0, 0, 0]
    this.coeffsInv = [0, 0, 1/dstPts[0], 0, 0, 0, 0, 0]
} else if(dstPts[1] === dstPts[3] && dstPts[1] === dstPts[5] && dstPts[1] === dstPts[7]){
    this.coeffs = [0, 1, 0, 0, 0, dstPts[0], 0, 0]
    this.coeffsInv = [0, 1, 0, 0, 0, 1/dstPts[0], 0, 0]
}else {
    this.coeffs = getNormalizationCoefficients(this.srcPts, this.dstPts, false);
    this.coeffsInv = getNormalizationCoefficients(this.srcPts, this.dstPts, true);
}

This just maps everything to a line that is the height of the source quadrilateral and on the x coordinate that all the x points of the destination quadrilateral are on, which is fine for my use case, but I feel like there could be a better solution.

hey,
First of all very nice work done.
but I have problem installing via npm.(tried on with bower and loved your work)
though I reported problem in npm and npm-windows-update

Error is something like

npm ERR! Windows_NT 6.1.7601
npm ERR! argv "C:\Program Files\nodejs\node.exe" "C:\Users\alfanso\AppData\Roaming\npm\node_modules\npm\bin\npm-cli.js" "install" "perspective-transform"
npm ERR! node v4.2.3
npm ERR! npm v3.5.2
npm ERR! code ENOSELF

npm ERR! Refusing to install perspective-transform as a dependency of itself
npm ERR!
npm ERR! If you need help, you may report this error at:
npm ERR! https://github.com/npm/npm/issues

npm ERR! Please include the following file with any support request:
npm ERR! E:\node\perspective-transform\npm-debug.log

I'm trying to use this library, but I get weird results that I can't really explain.

Using this code below:

   const srcCorners = [
      491218.662528078, 6259800.43254993,
      491664.008009023, 6259799.53201322,
      491606.373219169, 6260054.09226945,
      491240.25960665, 6260028.56590027
    ]
    const dstCorners = [
      0, 0,
      100, 0,
      100, 100,
      0, 100
    ]
    const perspT = PerspT(srcCorners, dstCorners)
    console.log(perspT.transform(491438.780488201, 6259922.52984722))

Which when plotted looks like this:

I've got four corner points and a query point right in the center. I'm mapping this to a rectangle spanning (0,0) to (100, 100).
When I run this code, though, I get [-144.37178139160187, -125.00368410330502], whereas it should be around [54.644979834216294, 45.89394897084863].

Am I doing something wrong here?