# How to smooth STL blob?
**URL:** https://discourse.vtk.org/t/how-to-smooth-stl-blob/15634
**Category:** Web
**Created:** [May 16, 2025, 8:46am UTC](https://discourse.vtk.org/t/how-to-smooth-stl-blob/15634 "2025-05-16T08:46:50Z")
**Posts on this page:** 6
**Page:** 1
Here is my code. It is almost identical to this [example](https://kitware.github.io/vtk-js/examples/WindowedSincPolyDataFilter.html#Source)
```typescript
function StlModal(props: { ohifDicomSegBlob: any }) {
const vtkContainer = useRef(null);
async function getStl() {
const stlRequest = await fetch('http://localhost:3004/orthanc/get-stl-from-dicom-seg', {
method: "POST",
body: ohifDicomSegBlob,
});
const stlBlob = await stlRequest.blob();
const fullScreenRenderer = vtkFullScreenRenderWindow.newInstance({
background: [0, 0, 0],
rootContainer: vtkContainer.current,
});
const renderer = fullScreenRenderer.getRenderer();
const renderWindow = fullScreenRenderer.getRenderWindow();
const actor = vtkActor.newInstance();
renderer.addActor(actor);
const mapper = vtkMapper.newInstance({ interpolateScalarBeforeMapping: true });
actor.setMapper(mapper);
const cam = vtkCamera.newInstance();
renderer.setActiveCamera(cam);
cam.setFocalPoint(0, 0, 0);
cam.setPosition(0, 0, 10);
cam.setClippingRange(0.1, 50.0);
const stlReader = vtkSTLReader.newInstance();
const smoothFilter = vtkWindowedSincPolyDataFilter.newInstance({
nonManifoldSmoothing: 0,
numberOfIterations: 100,
passBand: 0.001,
});
const arrayBuffer = await stlBlob.arrayBuffer();
stlReader.parseAsArrayBuffer(arrayBuffer);
smoothFilter.setInputConnection(stlReader.getOutputPort());
mapper.setInputConnection(smoothFilter.getOutputPort());
renderer.resetCamera();
renderWindow.render();
}
return (
);
}
```
but instead of vtkHttpDataSetReader i use vtkSTLReader.
In this component i get dicom-seg blob generated by OHIF. make request to get STL blob and render it using VTK.
But numberOfIterations: 100 and passBand: 0.001 has no effect. With them or without i see this
non-smooth result
I expected something like this
---
i made these changes:
```typescript
const stlReader = vtkSTLReader.newInstance();
const normals = vtkPolyDataNormals.newInstance();
stlReader.setRemoveDuplicateVertices(1)
const smoothFilter = vtkWindowedSincPolyDataFilter.newInstance({
nonManifoldSmoothing: 0,
numberOfIterations: 100,
passBand: 0.001,
});
const arrayBuffer = await stlBlob.arrayBuffer();
stlReader.parseAsArrayBuffer(arrayBuffer);
smoothFilter.setInputConnection(stlReader.getOutputPort());
mapper.setInputConnection(normals.getOutputPort());
normals.setInputConnection(smoothFilter.getOutputPort());
```
and now it’s smooth. But very laggy, little mouse movement takes 10s, is it expected? from this point all depends on my cpu power?
i enabled these flags and it’s less laggy, but still unusable.
chrome://flags/#enable-unsafe-webgpu
chrome://flags/#enable-vulkan
In this [example](https://kitware.github.io/vtk-js/examples/WindowedSincPolyDataFilter.html#Live-example) it’s not laggy after changing properties
---
never mind.
i made these changes and its not laggy at all.
```typescript
smoothFilter.setInputConnection(stlReader.getOutputPort());
mapper.setInputConnection(normals.getOutputPort());
normals.setInputConnection(smoothFilter.getOutputPort());
smoothFilter.setInputData(stlReader.getOutputData());
mapper.setInputData(normals.getOutputData());
normals.setInputData(smoothFilter.getOutputData());
```
so i just added setInputData after setInputConnection. I have no idea why it helped
---
What if you try the following ?
```auto
smoothFilter.setInputConnection(stlReader.getOutputPort());
normals.setInputConnection(smoothFilter.getOutputPort());
mapper.setInputConnection(normals.getOutputPort());
normals.update();
```