Seems like there might be a display problem with Chrome, could it be due to having the 32 bit version of Chrome installed?
To enhance the quality, try two things. First, set a renderer attribute:
renderer.shadowMapType = THREE.PCFSoftShadowMap; // options are THREE.BasicShadowMap | THREE.PCFShadowMap | THREE.PCFSoftShadowMap
And then, increase the shadowmap size of your light using:
light.shadowMapWidth = 1024; // default is 512
light.shadowMapHeight = 1024; // default is 512
You can refer to this issue for more details: Quality of Three.js shadow in Chrome/MacOS?
“ It seems the antialiasing may vary depending on the browser and system you're using. Firefox currently doesn't support antialiasing at all. It could also be influenced by your graphics card and drivers. For instance, I don't get antialiasing in Chrome on my old mid-2009 MacBook Pro, but I do on my newer late-2012 machine.
You might want to consider utilizing the FXAA shader for antialiasing as a postprocessing step. More information on postprocessing can be found here.”
For further reading: Antialiasing not working in Three.js