we all love detailed shots but most of the time, more detail means more render time, or a lagging viewport, here are some tricks to use if you want to add more details into your renders
1 Cube maps
In computer graphics, cube mapping is a method of environment mapping that uses the six faces of a cube to map an enviroment background, this is how most hdri mapping works, but the problem with hdri you dont get as much control as you need, rotating them is tricky and they do not capture shadows or have a ground for your characters to stand on. you can project cubemap textures on a sphere and edit it for more interesting visuals.
if you want cube maps there is an Ai, for generating them via text prompts called skybox, it also has a new feature where you can just draw the details in.
or you can the addon hdri maker to get the same control.
2 Parallax Mapping
Parallax mapping or virtual displacement mapping is an enhancement of the bump mapping or normal mapping techniques applied to textures in 3D rendering applications and video games. To the end user, this means that textures such as stone walls will have more apparent depth and thus greater realism with less impact on render time.
Parallax mapping is implemented by displacing the texture coordinates at a point on the rendered polygon by a function of the view angle in tangent space and the value of the height map at that point. At steeper view-angles, the texture coordinates are displaced more, giving the illusion of depth due to parallax effects as the view changes.
blender does not support parallax mapping by default but addons like wparallax have support for parallax mapping.
3 Alpha maps
i think alpha maps are the most underrated way to adding detail in renders, take an example of artist Kaiwan Shaban, he uses character silhouettes in his renders to add visual interest, these are not 3d characters just a simple alpha texture on a plane, if you want to try them in your scene, you can download them on blendermarket.
4 light gobos
another way to use alpha maps are light gobos. where there is light, there is shadow, adding shadows of large objects in your scenes adds definition and depth to your renders. you can add large objects in your scenes and hope they will cast the shadows where you want them or simply use light gobos, which use a spotlight and a texture. the texture when added to the spotlight will be projected onto objects as the shadow, which gives more defined shadows without needing actual objects to cast real shadows.
light gobos are not simply black and with silhouettes of objects like trees and leaves, these are depth maps of objects, that is why if you look at shadows created by good gobos like the ones provided by the gobos light texture addon, you will see that shadows in some areas are out of focus than in other areas. this is the definition am talking about they also include animated ones and caustics.
like i said, alpha maps are an underrated way of adding detail to your renders, you can also use them to create massive forest like in the example of Alpha trees which is a blender addon, that uses this technique to create millions of trees without slowing down the viewport or render. its just a texture on a plane that is oriented towards the camera most of the time. the addon also handles optimization as having this many alpha textures can also be demanding.
this addon works with trees and vegetation but this can also be a crowd of people, grass and more.
6 Height displacement maps
a height map is one way to get detail on a mesh without adding it manually, height maps can be image , a video or procedure textures. its a way to displace geometry on a mesh, by using the luminance of a texture, pure white pixels will raise the vertices at that pixel by 1 unit, and pure black will raise the vertices at that pixel by -1 and pure gray will do nothing.
you can use height maps to add mountains, sculptures and more. a quick google search can avail hundreds of heightmaps to you, though they might not be high resolution, most of the time you dont need it anyway unless you are doing close ups, for that i would recommend addons like true terrain it uses similar techniques coupled with others to archive more detailed enviroments.
7 vector displacement
like height maps vector maps displace geometry according to the color of the pixel at a vertex but unlike height maps that do it in only the up or down direction, vector displacement maps do it in all directions.
another big difference between height maps and vector displacement maps is that vector maps can create geometry that folds over its self something you cant do with height maps.
in blender vector displacement can be created procedurally in the shader editor or used as a brush in scupting.
if you want some amazing examples of shader based vector displacement projects checkout this bundle from Node November where artists during the month of November challenge them selves to make amazing things using only nodes.
8 Normal Maps
In 3D computer graphics, normal mapping, or Dot3 bump mapping, is a texture mapping technique used for faking the lighting of bumps and dents – an implementation of bump mapping. It is used to add details without using more polygons.
this technique is the most popular technique for adding extra detail at no extra computation cost.
details added using normal maps do not require extra subdivisions on a mesh like height maps or vector displacement maps, for displacement maps the level of detail is directly linked to the number of subdivisions on your mesh which increases the render time of each frame.
normal maps are great at capturing and reflecting light on surfaces but what most people dont know that they are good at refracting light on glass surfaces.
if you have a glass object try adding a normal map and see the difference.
never underestimate the power of a good roughness map, roughness is used to determine how rough or shinny a surface is. most shader nodes in blender come with a roughness input, you can use the slider to input a single value, or you can plugin a texture to drive the roughness of the surface.
a good roughness texture can turn a boring render into one that everyone is obsessed with, if you want good roughness maps, you can search for grunge maps on google and a few will pop up, but make sure you get high resolution maps or the roughness will look weird or try these 4k versions on blendermarket
10 Proxies and imposters
sometimes rendering alot of detail is not so much a problem like working with lots of detail, for example if you are rendering trees, the process of rendering them might be faster than working with them in the viewport, since at any given point the viewport has to compute each tree in your scene.
and for a forest that can be 10s of thousands of trees, all these trees have to be accounted for when working in the viewport, but at render time, the computer only cares about what the camera sees which makes computations faster.
to make it easier to work while in the viewport proxies are used in place of trees, this can be a simple plane or cubes or impostors like ones generated by the instant imposter addon. This addon generates a lowpoly version of the tree which looks identical to the original and can be used as a proxy in the viewport or as the final version since it retains most of the detail from the original tree.
decals are details plastered on an object, decals are usually not part of the main object, but are rendered as though they are.
decals could be geometry detail like what the addon decal machine offers, the decal its self is texture on a plane rendered to look as actual geometry part of the main object. decalmachine addon does a great job at this and there decals come with parallax shading supported which makes the decals look fused to the object.
there are also texture decals like what my addon quick decals provides, these are details for adding quick texturing effects like, water damage, posters and more, this is a great way to add texture detail without uv unwrapping meshes or spending alot of time in photoshop.
12 Texture painting
sometimes especially for stylized renders, are great way to add detail is not to model it, but paint it in, this technique is great for optimization or simply achieving a style that is hard to get with polygon modeling or does not look right if not painted.
if you do texture painting and sculpting alot, you may want to try out this sculpt-paint wheel addon, that adds all your sculpting and painting brushes in a popup wheel for easy use
13 Render Optimization
while proxies are great for viewport optimization, there other ways you can optimize your project for less render time.
both cycles and eevee have options to set a texture size limit at render time, since large textures contribute alot to longer render times.
so setting a texture size limit helps especially since most of the time you dont need to use 2k or 4k textures for every model in your scene but if the limit is not set, the entire size of the texture will be used slowing down the render.
the only issue with this technique is that it limits the texture size for all objects in your scenes yet sometimes you want objects especially those close to the camera to have more resolution.
if you want more control over scene optimization, there is an addon for that called MemSaver by polygoniq.
this addon will dynamically change the texture size of the objects as the camera moves closer to them, giving them a smooth transition from low texture size to a high texture size.
those where some ways you can add detail to your renders without adding too much stress on your machine.