Recent content by grelf

For a beginners course using JavaScript see http://www.grelf.net/jscourse

Basic used to be the thing but the language that's now available to everyone is JavaScript. It works in any browser and every machine (even a phone) has a browser! For a beginners course see http://www.grelf.net/jscourse

JavaScript is the most accessible. All you need is a browser and a text editor. It is completely platform-independent and distributing your program is a doddle because you only have to put it on a web page. Then even smart phones can run it. It used to be said that JavaScript was not...

A new version of my GRIP application is now available, including the kind of distortion correction I believe you want. Read carefully my initial description here: http://www.grelf.net/new.html then I hope you will be able to download and use it. Please give me feedback on whether it does what...

I have nearly finished a new version which does the following. Use an image of a square array of dots, taken with the same optical set-up as you wish to correct. GRIP measures the positions of the dots and creates a regular grid of the same average spacing and orientation. It then knows what...

I am currently modifying GRIP so that correcting the lens distortion of a photo will be possible as a menu option, after a reference pattern of the kind I think you mean has been used to calibrate it. A programmer could do it with my API now but I'll make it so a non-programmer can do it.

You need to detect each spot as a shape, in terms of its boundary. Then you can calculate geometrical factors such as width, height, perimeter and, most usefully in your case, centroid (ie, the centre of graviity of all the pixels comprising the object. I do this kind of thing in my own image...

General relativity is all about acceleration (equivalence principle). Quantum theory never mentions acceleration. New object speeds and directions only arise from discrete interaction events. Is this the fundamental reason why the two theories are so hard to reconcile?

I have long been puzzled by the whole idea of delayed choice experiments with photons. In a photon's frame of reference there is no distance traveled between emission and absorption; the distance has contracted (Lorentz-Fitzgerald) to zero. More relevantly there is no time duration either...

The Robertson-Walker metric applies a time-dependent scale factor to model the expansion of the universe. The scale factor is only applied to the spatial coordinates (in the frame of the "comoving observer"). That is not covariant and it is hard to see how c could remain constant if the same...