[37] | 1 | % * This code was used in the following articles:
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| 2 | % * [1] Learning 3-D Scene Structure from a Single Still Image,
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| 3 | % * Ashutosh Saxena, Min Sun, Andrew Y. Ng,
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| 4 | % * In ICCV workshop on 3D Representation for Recognition (3dRR-07), 2007.
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| 5 | % * (best paper)
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| 6 | % * [2] 3-D Reconstruction from Sparse Views using Monocular Vision,
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| 7 | % * Ashutosh Saxena, Min Sun, Andrew Y. Ng,
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| 8 | % * In ICCV workshop on Virtual Representations and Modeling
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| 9 | % * of Large-scale environments (VRML), 2007.
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| 10 | % * [3] 3-D Depth Reconstruction from a Single Still Image,
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| 11 | % * Ashutosh Saxena, Sung H. Chung, Andrew Y. Ng.
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| 12 | % * International Journal of Computer Vision (IJCV), Aug 2007.
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| 13 | % * [6] Learning Depth from Single Monocular Images,
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| 14 | % * Ashutosh Saxena, Sung H. Chung, Andrew Y. Ng.
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| 15 | % * In Neural Information Processing Systems (NIPS) 18, 2005.
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| 16 | % *
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| 17 | % * These articles are available at:
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| 18 | % * http://make3d.stanford.edu/publications
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| 19 | % *
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| 20 | % * We request that you cite the papers [1], [3] and [6] in any of
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| 21 | % * your reports that uses this code.
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| 22 | % * Further, if you use the code in image3dstiching/ (multiple image version),
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| 23 | % * then please cite [2].
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| 24 | % *
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| 25 | % * If you use the code in third_party/, then PLEASE CITE and follow the
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| 26 | % * LICENSE OF THE CORRESPONDING THIRD PARTY CODE.
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| 27 | % *
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| 28 | % * Finally, this code is for non-commercial use only. For further
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| 29 | % * information and to obtain a copy of the license, see
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| 30 | % *
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| 31 | % * http://make3d.stanford.edu/publications/code
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| 32 | % *
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| 33 | % * Also, the software distributed under the License is distributed on an
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| 34 | % * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
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| 35 | % * express or implied. See the License for the specific language governing
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| 36 | % * permissions and limitations under the License.
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| 37 | % *
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| 38 | % */
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| 39 | function doIntersect = lineSegIntersect(x,y) |
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| 40 | |
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| 41 | %% we need to find out if the line segment xy(1)xy(2) intersects the line |
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| 42 | %% segment xy(3)xy(4) |
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| 43 | |
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| 44 | %% this is true if and only if xy(1) and xy(2) lie on opposite sides of |
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| 45 | %% segment xy(3)xy(4) and xy(3) and xy(4) lie on opposite sides of the |
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| 46 | %% segment xy(1)xy(2) |
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| 47 | |
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| 48 | %% we use the convex hull trick and check if it is a quadilateral with |
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| 49 | %% alternating vertices |
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| 50 | |
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| 51 | disp('lineSegIntersect') |
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| 52 | doIntersect=logical(0); |
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| 53 | if ((x(2)-x(1))~=0) |
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| 54 | m1 = (y(2)-y(1))/(x(2)-x(1)); |
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| 55 | c1 = y(1)-m1*x(1); |
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| 56 | chk1=(((y(3)-m1*x(3)-c1)*(y(4)-m1*x(4)-c1))<0); |
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| 57 | else |
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| 58 | chk1=((x(3)-x(1))*(x(4)-x(1))<0); |
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| 59 | end |
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| 60 | |
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| 61 | if ((x(4)-x(3))~=0) |
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| 62 | m2 = (y(4)-y(3))/(x(4)-x(3)); |
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| 63 | c2 = y(3)-m2*x(3); |
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| 64 | chk2=(((y(1)-m2*x(1)-c2)*(y(2)-m2*x(2)-c2))<0); |
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| 65 | else |
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| 66 | chk2=((x(1)-x(3))*(x(2)-x(3))<0); |
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| 67 | end |
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| 68 | |
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| 69 | if (chk1 && chk2) |
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| 70 | doIntersect=logical(1); |
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| 71 | end |
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| 72 | |
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| 73 | % k=convhull(x,y); |
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| 74 | % if length(k)==5 |
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| 75 | % if ((k(1)==1)||(k(1)==2)) |
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| 76 | % if ((k(2)==3)||(k(2)==4)) |
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| 77 | % if ((k(3)==1)||(k(3)==2)) |
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| 78 | % if ((k(4)==3)||(k(4)==4)) |
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| 79 | % doIntersect=logical(1); |
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| 80 | % end |
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| 81 | % end |
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| 82 | % end |
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| 83 | % elseif ((k(1)==3)||(k(1)==4)) |
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| 84 | % if ((k(2)==1)||(k(2)==2)) |
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| 85 | % if ((k(3)==3)||(k(3)==4)) |
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| 86 | % if ((k(4)==1)||(k(4)==2)) |
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| 87 | % doIntersect=logical(1); |
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| 88 | % end |
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| 89 | % end |
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| 90 | % end |
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| 91 | % end |
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| 92 | % end |
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