Robotic systems for determining an angular degree of freedom of a medical device in luminal networks

1. A method of facilitating navigation of an anatomical luminal network of a patient, the method, executed by a set of one or more computing devices, comprising:

receiving imaging data captured by an imaging device at a distal end of an instrument positioned within the anatomical luminal network, the anatomical luminal network including a first branch and a second branch;

generating a depth map based at least in part on the imaging data;

identifying:

a first depth criterion associated with the depth map and representing a position of the first branch; and

a second depth criterion associated with the depth map and representing a position of the second branch;

determining a separation distance between the first depth criterion and the second depth criterion;

accessing one or more features associated with a virtual image, the virtual image simulated from a viewpoint of a virtual imaging device positioned at a virtual location within a virtual luminal network representative of the anatomical luminal network, the virtual luminal network including a virtual first branch corresponding to the first branch and a virtual second branch corresponding to the second branch; and

determining a value representing at least one angular degree of freedom of the distal end of the instrument within the anatomical luminal network based at least in part on the separation distance and the one or more features associated with the virtual image.

2. The method of claim 1 , wherein the anatomical luminal network includes a third branch bifurcating into the first branch and the second branch, the method further comprising determining an insertion depth of the distal end of the instrument within the third branch based on the virtual location of the virtual image.

3. The method of claim 2 , wherein the value representing the at least one angular degree of freedom of the distal end of the instrument represents a roll of the distal end of the instrument.

4. The method of claim 3 , further comprising:

generating an electromagnetic field around the anatomical luminal network; and

determining a registration between a coordinate frame of the virtual luminal network and a coordinate frame of the electromagnetic field based on the insertion depth and the roll of the distal end of the instrument.

5. The method of claim 1 , wherein said generating the depth map based at least in part on the imaging data involves calculating, for each pixel of a plurality of pixels of the imaging data, a depth value representing an estimated distance between the imaging device and a tissue surface within the anatomical luminal network corresponding to the pixel.

6. The method of claim 5 , further comprising:

identifying a first pixel of the plurality of pixels corresponding to the first depth criterion in the depth map;

determining a first location of the first branch in the imaging data based on a position of the first pixel;

identifying a second pixel of the plurality of pixels corresponding to the second depth criterion in the depth map; and

determining a second location of the second branch in the imaging data based on a position of the second pixel.

7. The method of claim 6 , further comprising:

determining that the first pixel has a greater depth value than the second pixel; and

identifying that the first location corresponds to the first branch based on said determining that the first pixel has the greater depth value.

8. The method of claim 1 , wherein:

the first depth criterion represents a most distant imaged tissue within the first branch; and

the second depth criterion represents a most distant imaged tissue within the second branch.

9. The method of claim 6 , wherein:

the first depth criterion corresponds to a first local maximum in a first region of depth values around the first pixel; and

the second depth criterion corresponds to a second local maximum in a second region of depth values around the second pixel.

10. The method of claim 1 , further comprising determining the value representing the at least one angular degree of freedom of the distal end of the instrument based on an angular distance between a first position of the first branch in the imaging data and a second position of the virtual first branch in the virtual image.

11. A system configured to facilitate navigation of an anatomical luminal network of a patient, the system comprising:

an imaging device at a distal end of an instrument;

at least one computer-readable memory having stored thereon executable instructions; and

one or more processors in communication with the at least one computer-readable memory and configured to execute the executable instructions to cause the system to:

receive imaging data captured by the imaging device with the distal end of the instrument positioned within the anatomical luminal network, the anatomical luminal network including a first branch and a second branch;

generate a depth map representing the image data;

identify first and second pixels of the depth map representing a first positioning of the first branch and the second branch in the imaging data;

determine a quantity of separation between the first and second pixels of the depth map;

access one or more features associated with a virtual image, the virtual image simulated from a viewpoint of a virtual imaging device positioned at a virtual location within a virtual luminal network representative of the anatomical luminal network, the virtual luminal network including a virtual first branch corresponding to the first branch and a virtual second branch corresponding to the second branch, the one or more features associated with the virtual image representing a second positioning of the virtual first branch and the virtual second branch in the virtual image; and

determine a value representing at least one angular degree of freedom of the distal end of the distal end of the instrument within the anatomical luminal network based at least in part on the quantity of separation and the one or more features associated with the virtual image.

12. The system of claim 11 , wherein the anatomical luminal network includes a third branch bifurcating into the first branch and the second branch, and wherein the one or more processors are configured to execute the executable instructions to cause the system to determine an insertion depth of the distal end of the instrument within the third branch based on the virtual location of the virtual image.

13. The system of claim 12 , wherein the value representing the at least one angular degree of freedom of the distal end of the instrument indicates a roll of the distal end of the instrument.

14. The system of claim 13 , wherein the one or more processors are further configured to execute the executable instructions to cause the system to:

generate an electromagnetic field around the anatomical luminal network; and

determine a registration between a coordinate frame of the virtual luminal network and a coordinate frame of the electromagnetic field based on the insertion depth and the roll of the distal end of the instrument.

15. The system of claim 11 , wherein the one or more processors are configured to execute the executable instructions to cause the system to:

generate the depth map at least in part by calculating, for each pixel of a plurality of pixels of the imaging data, a depth value representing an estimated distance between the imaging device and a tissue surface within the anatomical luminal network corresponding to the pixel;

identify the first pixel as corresponding to a first depth criterion in the depth map;

determine a first location of the first branch in the imaging data based on a position of the first pixel;

identify the second pixel as corresponding to a second depth criterion in the depth map; and

determine a second location of the second branch in the imaging data based on a position of the second pixel.

16. The system of claim 15 , wherein the one or more processors are further configured to execute the executable instructions to cause the system to:

determine that the first pixel has a greater depth value than the second pixel; and

identify that the first location corresponds to the first branch based on said determination that the first pixel has the greater depth value.

17. The system of claim 15 , wherein:

the first depth criterion represents a most distant imaged tissue within the first branch; and

the second depth criterion represents a most distant imaged tissue within the second branch.

18. The system of claim 15 , wherein:

the first depth criterion corresponds to a first local maximum in a first region of depth values around the first pixel; and

the second depth criterion corresponds to a second local maximum in a second region of depth values around the second pixel.

19. The system of claim 11 , wherein the one or more processors are further configured to execute the executable instructions to cause the system to determine the value representing the at least one angular degree of freedom of the distal end of the instrument based on an angular distance between a first position of the first branch in the imaging data and a second position of the virtual first branch in the virtual image.

20. A non-transitory computer readable storage medium having stored thereon instructions that, when executed, cause at least one computing device to:

receive imaging data captured by an imaging device at a distal end of an instrument positioned within an anatomical luminal network, wherein the anatomical luminal network includes a first branch and a second branch;

generate depth map data based at least in part on the imaging data;

identify first and second depth map features in the depth map data representing a first positioning of the first branch and the second branch in the imaging data;

determining a first distance between the first and second depth map features;

access a virtual image including a virtual first branch corresponding to the first branch and a virtual second branch corresponding to the second branch, the virtual first branch and the virtual second branch being separated by a second distance in the virtual image; and

determine a value representing at least one angular degree of freedom of the distal end of the instrument within the anatomical luminal network based at least in part on the first distance and the second distance.

21. The non-transitory computer readable storage medium of claim 20 , wherein:

the anatomical luminal network includes a third branch bifurcating into the first branch and the second branch; and

the instructions, when executed, further cause the at least one computing device to determine an insertion depth of the distal end of the instrument within the third branch based on a virtual location of the virtual image.

22. The non-transitory computer readable storage medium of claim 21 , wherein the value representing the at least one angular degree of freedom of the distal end of the instrument comprises a roll of the distal end of the instrument.

23. The non-transitory computer readable storage medium of claim 22 , wherein the instructions, when executed, further cause the at least one computing device to:

generate an electromagnetic field around the anatomical luminal network; and

determine a registration between a coordinate frame of a virtual luminal network associated with the virtual image and a coordinate frame of the electromagnetic field based on the insertion depth and the roll of the distal end of the instrument.

24. The non-transitory computer readable storage medium of claim 20 , wherein the instructions, when executed, cause the at least one computing device to:

generate the depth map data by calculating, for each pixel of a plurality of pixels of the imaging data, a depth value representing an estimated distance between the imaging device and a tissue surface within the anatomical luminal network corresponding to the pixel;

identify a first pixel of the plurality of pixels corresponding to a first depth criterion in the depth map;

determine a first location of the first branch in the imaging data based on a position of the first pixel;

identify a second pixel of the plurality of pixels corresponding to a second depth criterion in the depth map; and

determine a second location of the second branch in the imaging data based on a position of the second pixel.

25. The non-transitory computer readable storage medium of claim 24 , wherein the instructions, when executed, further cause the at least one computing device to:

determine that the first pixel has a greater depth value than the second pixel; and

determine that the first location corresponds to the first branch based on the determination that the first pixel has the greater depth value.

26. The non-transitory computer readable storage medium of claim 24 , wherein the first depth criterion represents a most distant imaged tissue within the first branch, and wherein the second depth criterion represents a most distant imaged tissue within the second branch.

27. The non-transitory computer readable storage medium of claim 24 , wherein the first depth criterion corresponds to a first local maximum in a first region of depth values around the first pixel, and wherein the second depth criterion corresponds to a second local maximum in a second region of depth values around the second pixel.

28. The non-transitory computer readable storage medium of claim 20 , wherein the instructions, when executed, further cause the at least one computing device to determine the value representing the at least one angular degree of freedom of the distal end of the instrument based on an angular distance between a first position of the first branch in the imaging data and a second position of the virtual first branch in the virtual image.