Somebody knows how it's possible to have so good quality for the 3D Objects like here http://showroom.littleworkshop.fr/? The objects are exported at this quality from 3DsMax or Blender or something similar, or the quality it's improved in threejs? As far I saw, the project was created with threejs. Any information regarding this project it will be helpful.
Thank you.
Question of quality is subjective. A better question would be "how can I create a scene using three.js with photo-realistic lighting and materials".
So here's an answer to that. There are a few points that make the example you provided look good:
1 - lighting. The example uses a mixture of direct and ambient lighting. It is practically impossible to generate such lighting in real time in three.js (or any other 3d package for that matter) with the current state of the art on commodity hardware. So, you need to use light-maps. Light maps are pre-rendered textures of light and shadow, they can take a long time to generate, but look incredible, as demonstrated by example you mentioned. You can use Blender's Cycles renderer to generate light maps using "Bake" feature. The topic of lightmap generation is really outside of the scope of the question.
2 - Physically based materials. This is used to refer to material models that have excellent representation of real-life materials beyond "plastic". Three.js had at least 1 such maretial: StandardMaterial which is based on Metalness/Roughness/Albedo model (https://threejs.org/examples/?q=material#webgl_materials_standard)
good luck!