Method and system for determining a boundary surface network

1. A method for determining a boundary surface network of a tubular object, comprising:

providing an ordered series of contours on the basis of image data in a source space;

specifying a transformation function for at least two consecutive contours in the ordered series, from the source space into a unit space, the unit space being a three-dimensional Euclidean space having a normalized length, width and height, and which is different from the source space;

creating a unit space segment object in the unit space on the basis of the at least two consecutive contours;

determining a local signed distance function in the unit space for the unit space segment object;

determining relative positional information of a query point in the source space from a surface of a segment object in the source space, the segment object being based on the consecutive contours, on the basis of the local signed distance function in the unit space and using the transformation function; and

creating the boundary surface network on the basis of the determined relative positional information; wherein the contours are freeform contours.

2. The method of claim 1 , wherein each unit space segment object is assigned a dedicated transformation function for transformation into the unit space.

3. The method of claim 1 , wherein the contours in each case are transformed into a circular boundary edge which lies in a plane in the unit space in each case, and wherein the space segment object comprises the boundary edges of the contours.

4. The method of claim 3 , wherein the unit space segment object is bounded at least sectionally by a circumferential surface that is formed by the shortest connections between two boundary edges of the contours.

5. The method of claim 4 , wherein the planes of the boundary edges in the unit space are so disposed as to be tilted by an angle relative to each other.

6. The method of claim 4 , wherein the boundary edges of two different contours include one or more shared points in the unit space.

7. The method of claim 3 , wherein the planes of the boundary edges in the unit space are so disposed as to be tilted by an angle relative to each other.

8. The method of claim 3 , wherein the boundary edges of two different contours include one or more shared points in the unit space.

9. The method of claim 1 , wherein values of the signed distance function represent separations in the unit space from the surface of the unit space segment object.

10. The method of claim 1 , wherein a global position indicator function is determined for a plurality of unit space segment objects on the basis of the signed distance functions of the unit space segment objects.

11. The method of claim 1 , further comprising:

providing a representation of the tubular object on the basis of the image data, wherein the representation includes the ordered series of contours;

providing local measurement information for points of the representation;

creating a breakdown structure depiction of the tubular object by way of breakdown cells including different spatial extents, based on the local measurement information; and

deriving a boundary surface network on the basis of the created breakdown structure depiction.

12. A computer program product, including a non-transitory computer-readable storage medium storing sections of program code that, when executed, cause at least one processor at a boundary surface network determination system to perform the method of claim 1 .

13. The method of claim 1 , wherein the tubular object is a hollow organ.

14. A non-transitory computer readable medium including program segments for, when executed on at least one processor at a boundary surface network determination system, causing the boundary surface network determination system to implement the method of claim 1 .

15. The method of claim 1 , wherein the source space is based on a measurement space of an imaging system used to obtain the image data.

16. A boundary surface network determination system for determining a boundary surface network of a tubular object, comprising

an input interface, configured to supply an ordered series of contours on the basis of image data;

a segment object determination unit including a computer system configured to execute computer-readable instructions to

specify a transformation function for respectively transforming consecutive contours in the ordered series of contours from a source space into a unit space, the unit space being a three-dimensional Euclidean space having a normalized length, width and height, and which is different from the source space, and

create a unit space segment object in the unit space on the basis of the consecutive contours;

a distance determination unit, configured to determine a separation from a unit space segment object on the basis of a signed distance function established for each segment object in the unit space;

a position determination unit, configured to determine relative positional information of a query point in the source space from a surface of a segment object in the source space, said segment object being based on the consecutive contours, on the basis of the local signed distance function; and

an output interface, configured to supply a boundary surface network on the basis of a multiplicity of relative positional information determined via the position determination unit; wherein the contours are freeform contours.

17. The boundary surface network determination system of claim 16 , wherein the tubular object is a hollow organ.