Debarati,

In software, the word "engine" is used to refer to the core program that delivers a certain function. Think of a car: if you only have the engine, you can't drive; you also need the body, steering wheel, brakes, etc.

In software you need a user interface that makes the engine accessible. SH3D uses Sunflow as the render engine. As a user you can't see it, and you don't have direct access to it.

If you are not satisfied with the render engine that SH3D uses, you can use 3D view --> Export to OBJ format and an obj-file will be created. This allows you to use a different program, such as Blender, to make your render.

Hans