uniform density, matrix

Hi there, I am working on a new project starting last week, and hence I have been asking too many questions. Thanks for all who helped me.

Again, I have 3 simple queries looking for suggestions ASAP.

I am working on particle filter where I need to initialize the velocity, Intensity and position of (say N = 100) particles

Can you suggest me the M-code for

1. Drawing a value for the velocity from the uniform distribution

   v ~ U[-vmax, vmax] , where vmax = 1 unit/sec

2. Drawing a value for intensity from the uniform distribution

   I ~ U[Imin, Imax]  , where Imin = 10, Imax = 30

3. I have a matrix(or a frame(image) in my case) called 'z', say its a 3x3 frame.

x = [1.2, 0.45, 0.2, 0.25, 20]';

n=3;

m=3;

blur = 0.7;

a = 3.*randn(n,m);

for i=1:n

 for j=1:m

if i-x(1) < 3 && j-x(3) <3

      h(i,j) = x(5)/(2 * pi * (blur^2)) * exp(-((i-x(1))^2 + (j-x(3))^2)/ (2* (blur^2)))

else 

      h(i,j) = 0
  end

 end

end

z = a + h;

So, 'z' will be a 3x3 frame having certain values for the pixels.

The values in 'x' are [position in x-axis, velocity in x-axis, position in y-axis, velocity in y-axis, Intensity].

So the pixels in frame 'z' that fall in the vicinity of the position given my 'x' in x-y direction will have higher values(Intensity than others)

now, what I want is, the position of the particles should be initialized from the distribution q(x,y | z) is a uniform density over those regions in 'z' for which z(i,j) > T

T = threshold = 2

I need to draw values from that distribution.

Okay, I assume I have made myself clear. Can you friends please help!

Many thanks

P

Answer 1

[the cyclist]

Do you have the Statistics Toolbox? You can use the function unifrnd() to do at least some of what you need.

[PChoppala]

So that would solve my 1 & 2 points

1. x1 = unifrnd(-1,1,2,N)

2. x2 = unifrnd(10,30,1,N)

Can you help m out with the third?

Thanks