# vktPropPicker-\>picker report read access violation

**URL:** https://discourse.vtk.org/t/vktproppicker-picker-report-read-access-violation/6473
**Category:** Support
**Created:** [August 26, 2021, 9:15am UTC](https://discourse.vtk.org/t/vktproppicker-picker-report-read-access-violation/6473 "2021-08-26T09:15:09Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![jjjkk](https://discourse.vtk.org/user_avatar/discourse.vtk.org/jjjkk/32/3720_2.png) [@jjjkk](https://discourse.vtk.org/u/jjjkk)
#### Post date: [August 26, 2021, 9:15am UTC](https://discourse.vtk.org/t/vktproppicker-picker-report-read-access-violation/6473/1 "2021-08-26T09:15:09Z")

</div>

I am using both dicomseiral read and pickpixel example.  
[https://kitware.github.io/vtk-examples/site/Cxx/IO/ReadDICOMSeries/](https://kitware.github.io/vtk-examples/site/Cxx/IO/ReadDICOMSeries/)  
[https://kitware.github.io/vtk-examples/site/Cxx/Images/PickPixel/](https://kitware.github.io/vtk-examples/site/Cxx/Images/PickPixel/)  
Well, in my custom imageinteractorstyle I difen OnMouseMove function and code as in pickpixel exmaple.  
I got a exception triggered in my Qt debugger as below:

 ![image](https://discourse.vtk.org/uploads/default/original/2X/4/460d7ff6955e26eff2a175c1103e08a8fcea211f.png)

I check the debugger, it seems no nullptr:

 ![image](https://discourse.vtk.org/uploads/default/original/2X/d/d5649279402d9fc9f750fc27d45c267946bd293e.png)

The GetEventPosition function can return the right position infomation.  
I alse test the below code:

```auto
this->Picker->Pick(1.0,1.0,1.0,renderer);

```

it also return a exception.

Can someone help me?  
If you need more debug information, just tell me.

Part of my OnMouseMove function:

```auto
void myVtkInteractorStyleImage::OnMouseMove(){
    vtkRenderWindowInteractor* interactor =
        this->_ImageViewer->GetRenderWindow()->GetInteractor();
    vtkRenderer* renderer = this->_ImageViewer->GetRenderer();
    vtkImageActor* actor = this->_ImageViewer->GetImageActor();
    vtkImageData* image = this->_ImageViewer->GetInput();
    vtkInteractorStyle* style =
            dynamic_cast<vtkInteractorStyle*>(interactor->GetInteractorStyle());
    this->Picker->Pick(1.0,1.0,1.0,renderer);
    // Pick at the mouse location provided by the interactor
    this->Picker->Pick(interactor->GetEventPosition()[0],
                       interactor->GetEventPosition()[1], 0.0, renderer);

    // There could be other props assigned to this picker, so
    // make sure we picked the image actor
    vtkAssemblyPath* path = this->Picker->GetPath();
    bool validPick = false;
    ......
    ......

```