Dear all,
I have one question which I do not how to solve.
I want to simulate some realistic distortion in a synthetic way.
To be more clear, I have one example here. In the "slr-canon.xml"
file of database of LensFun, we can find the following:
<lens>
<maker>Canon</maker>
<model>Canon EF-S 18-55mm f/3.5-5.6</model>
<mount>Canon EF-S</mount>
<cropfactor>1.6</cropfactor>
<calibration>
<distortion model="ptlens" focal="18" a="0" b="0.003658"
c="-0.04063" />
<distortion model="ptlens" focal="21" a="0" b="0.004255"
c="-0.038513" />
<distortion model="ptlens" focal="24" a="0" b="-0.000965"
c="-0.019793" />
<distortion model="ptlens" focal="27" a="0" b="0.001701"
c="-0.014516" />
<distortion model="ptlens" focal="30" a="0" b="0.003199"
c="-0.012047" />
<distortion model="ptlens" focal="33" a="0" b="3.4e-05"
c="-0.005236" />
<distortion model="ptlens" focal="37" a="0" b="0.00556"
c="-0.016032" />
<distortion model="ptlens" focal="41" a="0" b="0.001585"
c="-0.007594" />
<distortion model="ptlens" focal="45" a="0" b="0.00577"
c="-0.015688" />
<distortion model="ptlens" focal="48" a="0" b="0.001543"
c="-0.003821" />
<distortion model="ptlens" focal="53" a="0" b="-0.001301"
c="0.001515" />
<distortion model="ptlens" focal="55" a="0" b="0.000426"
c="-0.001817" />
</calibration>
</lens>
From the website
http://lensfun.berlios.de/calibration-tutorial/lens-distortion.html,
we know that The model of "ptlens" has the formula as:
Ru = a * Rd^4 + b * Rd^3 + c * Rd^2 + (1 - a - b - c) * Rd.
Given the value of a, b and c, we can compute the value of Ru for
each Rd. And my question is what is Rd ? Is it the
sqrt((xd-xc)^2+(yd-yc)^2), where (xd, yd) is the coordinate of one
certain observed distorted pixel in the image ?
And what is the value for (xc, yc) ? Is it the center of image ?
In that case, if I have one 1000x1000 pixels image, (xc, yc) = (500,
500) ?
And xd and yd go from 0 to 1000, respectively ?
thank you very much,
zhongwei
------------------------------------------------------------------------------
Put Bad Developers to Shame
Dominate Development with Jenkins Continuous Integration
Continuously Automate Build, Test & Deployment
Start a new project now. Try Jenkins in the cloud.
http://p.sf.net/sfu/13600_Cloudbees
_______________________________________________
Lensfun-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/lensfun-users
