I am confused how to interpret the result of preforming a normalized correlation with a constant vector. Since you have to divide by the standard devation of both vectors (reference: http://en.wikipedia.org/wiki/Cross-correlation#Normalized_cross-correlation ) , if one of them is constant (say a...
@chiro - what kind of statistical techniques? Are you suggesting just computing a Euclidean style distance between local FFT components or something like that? Doesn't this ONLY contain frequency information, and no information in the spatial domain (i.e. the colors don't have to match at all)...
Yep, that's what I want :) Of course there isn't a perfect one, but I thought someone here might have an idea of a better one than a simple Euclidean distance.
Assume everything is quite low resolution. For instance, this picture of the entire house/grass/road is ~500x500.
Yes, only...
Hi Stephen,
The values are just the RGB pixel values.
It does very well in most cases, but when it fails (like the case I described), it fails miserably.
Yes, simple and fast is definitely a requirement.
I would like to avoid this at all costs :)
I hope this clarifies some...
I am trying to match little square patches in an image. You can imagine that these patches have been "vectorized" in that the values are reordered consistently into a 1D array. At first glance, it seems reasonable to simply do a Euclidean distance style comparison of two of these arrays to get a...
I know that the plane through the center of mass whose normal is the eigenvector corresponding to the smallest eigenvalue of the scatter matrix of a set of points is the best fit plane. I now want to do a "weighted least squares" - would I simply multiply the...
I guess even better would be some transform of each distance, so that:
f(d1)-f(p)=f(d2)-f(d1)
of course f() may not be exactly the same function, it may depending on the position (i.e. it could be
f(d1)-f(p)=g(d2)-g(d1)
or something like that).
See the image in the attached document. I am looking for a function which will make
f(d1-p)=f(d2-d1)=f(d3-d2) (see the very last part of the document)
I thought it would be as simple as dividing by the angle between the lines, but that doesn't seem to work. Is it reasonable to do this...
This is for mathematics students. Certainly if you study mathematics as your "field" then you should know these things. But engineers need not know them, and certainly people studying/practicing non-technical disciplines need not study them in high school.
Haha Manheis, as I was reading this thread I was thinking "how has no one posted the Worlfram TED talk??". I don't work for Wolfram either, but he is definitely right. Frankly, I am quite shocked that people here do not support this concept.
The people who will build the next-gen Maple style...
We all know
\int \frac{1}{x} dx = ln(x) + c
but if you try to apply the power rule for integration:
\int x^n dx = \frac{x^{n+1}}{n+1} + c
you get
\int x^{-1} dx = \frac{x^0}{0}
What can you learn from this/what does this mean?
David
You're right - the software may be fine. What I'm claiming though is that there needs to be many people from many fields working together to effectively produce a teaching tool. Typically this is done by the "content expert" alone. He is typically not versed in the "art" of teaching, or...
I am starting a project to develop, with a very diverse team, an open source, modular, web-based teaching tool for math, science, and engineering courses.
Here is a link to the full project description...
It's not the students fault, it's poor explanations! Don't sweat it - try to gather as many resources as you can to try to take bits and pieces from them all until it makes sense (what the authors should have done before writing a book...)
Dave
What applications are you interested in? Some fields use linear algebra heavily (computer vision) and some field use differential equations heavily (control theory).
Dave
I agree with Lorc Crc - I wouldn't do any "crossing out" in linear algebra - or even division for that matter - always move things around with the inverse operation.
Dave
Zaphos,
You have been very helpful, thanks! You are right on - I just thought it was an "error", but in fact it makes a lot of sense that the plane is the best fit to a set of sphere points.
Do you have a recommendation of a similar non-height field type of fitting procedure?
Thanks...
Where did you get a8 = -1 ?
It seems to work with some point sets, but for others (points sampled from a sphere, for example) the result is wrong (it says all of the coefficients are 0). Is there a reason that would happen?
Thanks,
David
1) Hm... isn't it just the standard least squares solution, or
Ax = b
x = A^{-1}b
or in this case since A is not invertible
x = pinv(A) b
where pinv is the pseudo inverse?
2) The second part - I was saying that in order to "see" this fit, I have a function in a toolbox that will plot...
I have a set of points and I want to find a "best fit quardric surface" through the points. I did the following:
1) Assume the function is in the form:
a x^2 + b y^2 + c xy + d x + e y + f = z
2) Make a nx6 matrix of the points put into (1), that is A=:
x1^2 y1^2 x1y1 x1 y1 1
x2^2 y2^2...
I think it would be very helpful if you guys used latex
The question should be
Proove that \lim {x \rightarrow a} \sqrt{x} = \sqrt{a}
And the first reply should be
start with
\sqrt{x}-\sqrt{a}=\frac{x-a}{\sqrt{x}+\sqrt{a}}
For basic things like this, latex only takes about a minute to...