Method and apparatus for automatic setting of rendering parameter for virtual endoscopy

1. A method for automatically setting a rendering parameter for a virtual endoscope for rendering images for virtual endoscopy, comprising the steps of:

calculating a histogram H 1 in area relatively close to said virtual endoscope;

calculating a histogram H 2 in area at a relatively greater distance to said endoscope;

calculating a histogram H 3 in area comprising H 1 and H 2 ;

identifying a given peak P 1 in histogram H 1 as material that will be set to be transparent;

identifying a given peak P 2 ≠P 1 in histogram H 2 as material that will be set to be oblique;

analyzing histogram H 3 and setting said rendering parameter at minimum between said peaks P 1 and P 2 ; and

rendering said image using said transfer function.

2. A method for automatically setting a rendering parameter for a virtual endoscope for rendering images for virtual endoscopy, comprising the steps of:

deriving a data set corresponding to an inside view of a viewing frustum of said endoscope;

rendering a plurality of images from said data set utilizing for each such image a respective rendering setting;

utilizing a predetermined criterion to determine a respective quality factor for each such image;

selecting as a preferred image one of said images exhibiting a quality factor having a maximum value of said respective quality factors;

storing a preferred rendering setting associated with said preferred image; and

utilizing said preferred rendering setting for rendering an image from said data set.

3. A method as recited in claim 2 , wherein said step of utilizing a predetermined criterion comprises utilizing a smoothness criterion.

4. A method as recited in claim 2 , wherein:

said step of rendering a plurality of images comprises utilizing ray casting for deriving a plurality of pixels for each of said plurality of images;

said step of utilizing a predetermined criterion comprises:

calculating a respective surface normal based on lighting criteria for each of said pixels, and

comparing a surface normal for a given pixel with a surface normal for a neighboring pixel in the same row to derive a first angle between their normals; and

said step of utilizing a predetermined criterion comprises assigning a quality factor having the highest value for an image exhibiting the least number of faults where a fault is defined as said first angle exceeding predetermined value.

5. A method as recited in claim 2 , wherein:

said step of rendering a plurality of images comprises:

utilizing ray casting for deriving a plurality of pixels for each of said plurality of images, and

arranging said pixels in rows and columns;

said step of utilizing a predetermined criterion comprises:

calculating a respective surface normal based on lighting criteria for each of said pixels, and

comparing a surface normal for a given pixel with a surface normal for a pixel in the same row to derive a first angle between their normals and with a surface normal of a pixel in the same column to derive a second angle b&ween their normals; and

said step of utilizing a predetermined criterion comprises assigning a quality factor having the highest value for an image exhibiting the least number of faults where a fault is defined as at least one of said first and second angles exceeding a predetermined value.

6. A method as recited in claim 2 , wherein:

said step of rendering a plurality of images comprises utilizing ray casting for deriving a plurality of pixels for each of said plurality of images;

said step of utilizing a predetermined criterion comprises: comparing color data for a given pixel with color data for a neighboring pixel, and deriving a color difference therebetween; and

said step of utilizing a predetermined criterion comprises assigning a quality factor having the highest value for an image exhibiting the least number of faults where a fault is defined as said color difference exceeding predetermined value.

7. A method as recited in claim 2 , wherein:

said step of rendering a plurality of images comprises: utilizing ray casting for deriving a plurality of pixels for each of said plurality of images;

arranging said pixels in rows and columns; said step of utilizing a predetermined criterion comprises comparing color data for a given pixel with color data for a pixel in the same row to derive a first color difference therebetween and with color data for a pixel in the same column to derive a second color difference therebetween; and

said step of utilizing a predetermined criterion comprises assigning a quality factor having the highest value for an image exhibiting the least number of faults where a fault is defined as at least one of said first and second color differences exceeding a predetermined value.

8. A method for automatically setting a rendering parameter for a virtual endoscope for rendering images for virtual endoscopy, comprising the steps of:

deriving a data set corresponding to an inside view of a viewing frustum of said endoscope;

rendering an image from said data set n times with parameter settings P i (0≠i<n) calculating a quality Q i for each such rendering; selecting a parameter P max which has highest quality Q max ≧Q i ; 0≦i≦n and 0≦max<n; and

render a final image with parameter setting P max .

9. Apparatus for automatically setting a rendering parameter for a virtual endoscope for rendering images for virtual endoscopy, comprising:

means for calculating a histogram H 1 in an area relatively close to said virtual endoscope;

means for calculating a histogram H 2 in an area at a relatively greater distance to said endoscope;

means for calculating a histogram H 3 in an area comprising H 1 and H 2 ;

means for identifying a given peak P 1 in histogram H 1 as material that will be set to be transparent;

means for identifying a given peak P 2 ≠P 1 in histogram H 2 as material that will be set to be oblique;

means for analyzing histogram H 3 and setting said rendering parameter at minimum between said peaks P 1 and P 2 ; and

means for rendering said image using said transfer function.

10. Apparatus for automatically setting a rendering parameter for a virtual endoscope for rendering images for virtual endoscopy, comprising:

means for deriving a data set corresponding to an inside view of a viewing frustum of said endoscope;

means for rendering an image from said data set n times with parameter settings P i (0≦i<n);

means for calculating a quality Q i for each such rendering;

means for selecting a parameter P max which has highest quality Q max ≧Q i ; 0≦i>n and 0≦max<n; and

means for render a final image with parameter setting P max .