# Predit a point position with the Homography matrix

**URL:** <https://forum.opencv.org/t/predit-a-point-position-with-the-homography-matrix/10571>\
**Category:** Uncategorized\
**Created:** [October 16, 2022, 2:06pm UTC](https://forum.opencv.org/t/predit-a-point-position-with-the-homography-matrix/10571 "2022-10-16T14:06:50Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Christophe\_Jacquelin](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/christophe_jacquelin/32/135_2.png) [@Christophe\_Jacquelin](https://forum.opencv.org/u/Christophe_Jacquelin)\
**Post date:** [October 16, 2022, 2:06pm UTC](https://forum.opencv.org/t/predit-a-point-position-with-the-homography-matrix/10571/1 "2022-10-16T14:06:50Z")

</div>

Hello,  
After computing the Homography transform with  
Mat h = findHomography(pts\_src, pts\_dst);

I want to predict the position of only one point from the source image to the destination image.  
How to use the Homography matrix to compute this only one point?  
Thank you

---

<div class="post-metadata">

**Author:** ![crackwitz](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/crackwitz/32/14_2.png) [@crackwitz](https://forum.opencv.org/u/crackwitz)\
**Post date:** [October 16, 2022, 2:17pm UTC](https://forum.opencv.org/t/predit-a-point-position-with-the-homography-matrix/10571/2 "2022-10-16T14:17:04Z")

</div>

what have you tried?

---

<div class="post-metadata">

**Author:** ![Christophe\_Jacquelin](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/christophe_jacquelin/32/135_2.png) [@Christophe\_Jacquelin](https://forum.opencv.org/u/Christophe_Jacquelin)\
**Post date:** [October 16, 2022, 2:49pm UTC](https://forum.opencv.org/t/predit-a-point-position-with-the-homography-matrix/10571/3 "2022-10-16T14:49:57Z")

</div>

```
perspectiveTransform( obj, obj_projection, homography_matrix);
for(std::size_t i=0;i<obj_projection.size();i++)
{
    std::cout<<obj_projection.at(i).x <<"," <<obj_projection.at(i).y<<std::endl;
}

```