Hello, I am facing the problem with shadow stripes on model

Materials : PBR based MeshStandardMaterial.

Lights used : hemisphier light, ambientLight, DirectionalLight
Directional light is used to display the shadow. Direction light’s position set to (0, 200, 50) and bias is set to -0.002

Problem: Some angles, black lines are visible on product, which is facing to the light.

Please find below jsfiddle for a demo. Can you help me to remove the shadow stipes?

https://jsfiddle.net/7a6gwjyn/

If I turn of castshadow and recieveshadow, I still see the lines. I think that is caused by a texture in your model.

If I change your material by replacing it with a MeshNormalMaterial, then I no longer see the lines.

 for (let i = 0; i < childrens.length; i++) {
   childrens[i].castShadow = true;
   childrens[i].receiveShadow = true;
   childrens[i].material =  new THREE.MeshNormalMaterial()
 }

@seanwasere

i have to use MeshStandardMaterial along with PBR flow, so would please try with MeshStandardMaterial only ?

same thing, your problem is not shadow

even if I turn off shadows in your renderer, it still see the lines

renderer = new THREE.WebGLRenderer({antialias: true});
renderer.setPixelRatio(window.devicePixelRatio);
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.outputEncoding = THREE.sRGBEncoding;
//renderer.shadowMap.enabled = true;
//renderer.shadowMap.type = THREE.PCFSoftShadowMap;
document.body.appendChild(renderer.domElement);

Let me check the other model and give you the exact issue

Tightening up the shadow frustum and descreasing the bias a bit fixes it:

      dirLight.shadow.camera.top = 170;
      dirLight.shadow.camera.bottom = -70;
      dirLight.shadow.camera.left = -150;
      dirLight.shadow.camera.right = 150;
      dirLight.shadow.camera.near = 25;
      dirLight.shadow.camera.far = 250;
      dirLight.shadow.bias = -0.005;

Updated fiddle: https://jsfiddle.net/mr1n5scL/

I concede, there is a shadow problem if you look really closely. This is usually solved by tweaking the bias.
Left, shadows enabled in renderer
Right, no shadows enabled in renderer

Can you try it with my updated fiddle? I can’t see any artifacts.

Oh no, I just changed the sliders and I broke it. This is a best as I can milk it with those pesky sliders.