# US 10,311,099 B2 · Method and system for 3D model database retrieval

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- Number: US 10,311,099 B2
- Document ID: US10311099B2
- Status: Granted
- Kind: B2
- Application number: 14/777,235
- Filed: 2014-03-14
- Published: 2016-03-03
- Granted: 2019-06-04
- Earliest claimed: 2013-03-15
- Assignees: Rejal Limited
- Applicants: Rejal Limited
- Inventors: Seena Rejal; Patrick Min
- Web page: https://patentgrep.com/patent/US10311099B2

## CPC

- G06F 16/5854: {using shape and object relationship}
- G06F 16/335: Filtering based on additional data, e.g. user or group profiles (filtering in web context G06F16/9535, G06F16/9536)
- G06F 16/532: Query formulation, e.g. graphical querying
- G06T 15/20: Perspective computation
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

The present invention relates to a computer-implemented method for 3D model database retrieval using a 3D model as a search input. The method converts the search input into a plurality of orthogonal 2D views; generates a signature for each 2D view; and then searches the 3D model database by comparing the plurality of generated signatures with signatures generated for each 3D model in the database. The signatures are compared with one another across at least two orthogonal rotations. A system for 3D model retrieval and a method and system for creating 3D model database are also disclosed.

## Claims

### Claim 1

A computer-implemented method for 3D model database retrieval using a 3D model as a search input, comprising:
converting the search input into a plurality of orthogonal 2D views;
generating a signature for each 2D view using a signature generating method which includes:
processing the 2D view to generate a boundary contour 2D view; and
removing small components from the boundary contour 2D view by detecting connected components of background pixels which comprise a number of pixels below a predetermined threshold and replacing background pixels corresponding to the detected connected components with object pixels; and
searching the 3D model database by comparing the plurality of generated signatures with signatures generated for each 3D model in the database;
wherein the signatures are compared with one another across at least two orthogonal rotations.

### Claim 2 (depends on 1)

A method as claimed in claim 1 wherein the signature generating method includes applying a distance transform function to the boundary contour 2D view to generate a distance transformed 2D view.

### Claim 3 (depends on 2)

A method as claimed in claim 2 wherein the distance transform function is a squared Euclidean distance transform (EDT) function.

### Claim 4 (depends on 2)

A method as claimed in claim 2 wherein the distance transform function is an L1 function.

### Claim 5 (depends on 2)

A method as claimed in claim 2 wherein the distance transform function is a Euclidean distance transform (EDT) function.

### Claim 6 (depends on 2)

A method as claimed in claim 2 wherein the signature generating method includes filtering the distance transformed 2D view using a filtering function such that distance values decay.

### Claim 7 (depends on 6)

A method as claimed in claim 6 wherein the filtering function is exponential.

### Claim 8 (depends on 6)

A method as claimed in claim 6 wherein the filtering function is linear.

### Claim 9 (depends on 6)

A method as claimed in claim 6 wherein the distance transformed 2D view is inverted before the filtering, such that the zero distance values are set to a predetermined maximum value and during the filtering the distance values decay to zero.

### Claim 10 (depends on 9)

A method as claimed in claim 9 wherein distance values below a specific threshold are set to zero.

### Claim 11 (depends on 6)

A method as claimed in claim 6 wherein the filtering function is:
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where M Is a squared threshold distance and wherein SExy is the squared EDT value for a pixel at x,y.

### Claim 12 (depends on 1)

A method as claimed in claim 1 wherein each 3D model in the database includes a plurality of signatures generated from orthogonal 2D views of that 3D model.

### Claim 13 (depends on 12)

A method as claimed in claim 12 wherein the plurality of generated signatures are compared with the signatures for the 3D models of the database by:
comparing each of the plurality of signatures of the search input with each of the plurality of signatures of a 3D model of the database across at least two orthogonal rotations;
wherein the smallest distance value of the comparisons against the 3D model of the database is the distance between the search input and the 3D model of the database.

### Claim 14 (depends on 1)

A method as claimed in claim 1 wherein the search input is converted into three orthogonal 2D views.

### Claim 15 (depends on 1)

A method as claimed in claim 1 wherein a user providing the search input also defines a strictness level used within the method to determine a level of matching between the search input and the 3D models in the database.

### Claim 16

A computer-implemented method for 3D model database retrieval using a 3D model as a search input, comprising:
converting the search input into a plurality of orthogonal 2D views;
generating a signature for each 2D view using a signature generating method which includes:
processing the 2D view to generate a boundary contour 2D view; and
removing small components from the boundary contour 2D view by detecting connected components of object pixels which comprise a number of pixels below a predetermined threshold and replacing the object pixels within the detected connected components with background pixels; and
searching the 3D model database by comparing, across at least two orthogonal rotations, the plurality of generated signatures with signatures generated for each 3D model in the database.

### Claim 17

A computer-implemented method for 3D model database retrieval using a 3D model as a search input, comprising:
converting the search input into a plurality of orthogonal 2D views;
generating a signature for each 2D view using a signature generating method which includes:
processing the 2D view to generate a boundary contour 2D view;
applying a distance transform function to the boundary contour 2D view to generate a distance transformed 2D view; and
filtering the distance transformed 2D view using a filtering function:
1
2
SE
x
,
y
/
M
·
(
M
-
SE
x
,
y
)
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M
-
SE
x
,
y
>
0
0
⋀
M
-
SE
x
,
y
≤
0
where M is a squared threshold distance and SExy is the squared EDT value for a pixel at x,y; and
searching the 3D model database by comparing, across at least two orthogonal rotations, the plurality of generated signatures with signatures generated for each 3D model in the database.