::New();
cellPicker->Pick(clickPos[0], clickPos[1], 0, this->GetDefaultRenderer());
//if something was picked
if( picker->GetActor() && cellPicker->GetCellId() != -1 ) {
// Output the probed value at the picked location.
vtkDataSet* dataSet = cellPicker->GetDataSet();
vtkCellData* cellData = dataSet->GetCellData();
vtkDataArray* dataArray = cellData->GetScalars();
if( dataArray->GetNumberOfComponents() <= 200 ){
double values[200]; //200 is a fairly large number of scalar fields.
dataArray->GetTuple( cellPicker->GetCellId(), values );
QString valuesText = "NO VALUES";
for( int i = 0; i < dataArray->GetNumberOfComponents(); ++i )
if( i == 0)
valuesText = QString::number(values[0]);
else
valuesText = valuesText + "; " + QString::number(values[i]);
std::cout << "Picked value(s): " << valuesText.toStdString() << std::endl;
} else
std::err << "Probing not possible if VTK object has more than 200 scalar fields in it." << std::endl;
}
(...)
```
For the complete example how I do probing can be found [here](https://github.com/PauloCarvalhoRJ/gammaray/blob/master/viewer3d/v3dmouseinteractor.cpp).
---
### Author:  [@flaviu2](https://discourse.vtk.org/u/flaviu2)
#### Post date: [February 5, 2020, 5:58pm UTC](https://discourse.vtk.org/t/convert-vtkproppicker-value-to-vtkvoxel-values/2549/3 "2020-02-05T17:58:12Z")
Paulo, thank you for your interest. Some light coming to my mind after I read your code. Still, I have some unknowns. I have tried the following code:
```
vtkPropPicker* pPicker = vtkPropPicker::New();
pPicker->Pick(nPosition[0], nPosition[1], 0, m_pRenderer);
vtkCellPicker* pCellPicker = vtkCellPicker::New();
pCellPicker->Pick(nPosition[0], nPosition[1], 0, m_pRenderer);
TRACE("==%p\t%d\n", pPicker->GetActor(), pCellPicker->GetCellId());
```
and after I made click on my 3d volume, on a tooth, I got always pPicker-\>GetActor() as NULL:
| ==0000000000000000 | 2155982 |
| --- | --- |
| ==0000000000000000 | 4525593 |
| ==0000000000000000 | 4866664 |
I don’t know why … could you tell me ?
After that code, I wrote:
```
if (pPicker->GetActor() && -1 != pCellPicker->GetCellId())
{
vtkDataSet* pDataSet = pCellPicker->GetDataSet();
vtkCellData* pCellData = pDataSet->GetCellData();
vtkDataArray* pArrData = pCellData->GetScalars();
if (pArrData->GetNumberOfComponents() <= 200)
{
double* dValue = pArrData->GetTuple(pCellPicker->GetCellId());
for (int i = 0; i < pArrData->GetNumberOfComponents(); ++i)
{
TRACE(">>>%f\n", dValue[i]);
}
}
}
pCellPicker->Delete();
pPicker->Delete();
```
of course, is never enter there …
---
### Author:  [@Paulo\_Carvalho](https://discourse.vtk.org/u/Paulo_Carvalho)
#### Post date: [February 5, 2020, 6:58pm UTC](https://discourse.vtk.org/t/convert-vtkproppicker-value-to-vtkvoxel-values/2549/4 "2020-02-05T18:58:33Z")
Since your case is a volume, maybe the object you’re picking is not a subclass of `vtkActor`. If you are picking volume slices (`vtkImageSlice`), then `GetActor()` will return `nullptr` indeed.
Take a look at the [`vtkProp` family](https://vtk.org/doc/nightly/html/classvtkProp.html). Then locate the visual VTK class that you’re using to render your image there. After that, you have to call the adequate method instead of `getActor()`. Maybe `GetProp3D()` will do.
---
### Author:  [@flaviu2](https://discourse.vtk.org/u/flaviu2)
#### Post date: [February 6, 2020, 9:12am UTC](https://discourse.vtk.org/t/convert-vtkproppicker-value-to-vtkvoxel-values/2549/5 "2020-02-06T09:12:11Z")
I come back to new results, hoping to learn as much as as can 🙂
Here is my new trial code:
```
vtkVolumePicker* pPicker = vtkVolumePicker::New();
pPicker->Pick(nPosition[0], nPosition[1], 0, m_pRenderer);
vtkCellPicker* pCellPicker = vtkCellPicker::New();
pCellPicker->Pick(nPosition[0], nPosition[1], 0, m_pRenderer);
TRACE("==%p\t%d\n", pPicker->GetActor(), pCellPicker->GetCellId());
==0000000000000000|5175224|
==0000000000000000|7797620|
```
but has the same result … didn’t used the right picker ? if I didn’t, what should be the right picker ?
Thank you for any response, this my main source of VTK learning (beside VTK documentation and examples) … so, don’t hesitate to write me anything of what I could learn here 🙂
Regards,
Flaviu.
---
### Author:  [@Paulo\_Carvalho](https://discourse.vtk.org/u/Paulo_Carvalho)
#### Post date: [February 7, 2020, 1:47pm UTC](https://discourse.vtk.org/t/convert-vtkproppicker-value-to-vtkvoxel-values/2549/6 "2020-02-07T13:47:03Z")
Hello,
Have you tried `GetProp3D()` instead of `GetActor()`? If the visual object you’re picking is not a `vtkActor` you have to use some other `Get*()` method of `pPicker`.
cheers,
Paulo
---
### Author:  [@flaviu2](https://discourse.vtk.org/u/flaviu2)
#### Post date: [February 9, 2020, 9:50am UTC](https://discourse.vtk.org/t/convert-vtkproppicker-value-to-vtkvoxel-values/2549/7 "2020-02-09T09:50:04Z")
With **vtkVolumePicker::GetProp3D** I got the pointer of the volume. Thank you !!!