contourArea example is wrong (Bug #967)

Added by Michael Richards almost 14 years ago. Updated almost 14 years ago.

Status:Done Start date:
Priority:Normal Due date:
Assignee:Ilya Lysenkov % Done:

0%
Category:documentation
Target version:-
Affected version: Operating System:
Difficulty: HW Platform:
Pull request:

Description

The docs page at: http://opencv.willowgarage.com/documentation/cpp/imgproc_structural_analysis_and_shape_descriptors.html#cv-contourarea

Gives the following example:
vector<Point> contour;
contour.push_back(Point2f(0, 0));
contour.push_back(Point2f(10, 0));
contour.push_back(Point2f(10, 10));
contour.push_back(Point2f(5, 4));

double area0 = contourArea(contour);
vector<Point> approx;
approxPolyDP(contour, approx, 5, true);
double area1 = contourArea(approx);

cout << "area0 =" << area0 << endl <<
"area1 =" << area1 << endl <<
"approx poly vertices" << approx.size() << endl;

The library does not seem to implicitly convert the vector<Point> into a Mat so this example does not work. I suspect the calls to contourArea(approx) should read: contourArea(Mat(approx))

History

#1
Updated by Ilya Lysenkov almost 14 years ago

  • Status deleted (Open)

#2
Updated by Ilya Lysenkov almost 14 years ago

Yes, you were right, the correct version had to be contourArea(Mat(approx)). But the new InputArray class (in trunk) works as a proxy type for Mat, vector and others types. So the example is compiled successfully now using the trunk version.

  • Status set to Done
  • (deleted custom field) set to obsolete

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