I wanted to talk about this a bit - I have my own ideas but I wanted to see what people thought about it. I'll add image examples as I find them.
A lot of concepts I see are beautiful to look at but I don't think people aspiring to be concept artists always understand what a 3d artist needs in respect to plan views - details etc.
So what is most useful to 3d artists in a concept?
These ideas should apply to Characters, Props, Environments, Vehicles and Accessories and more.
3 quarter Views: 3/4 front and 3/4 back describe the character in 360 degrees nicely. Most character artists would find this to be enough information to guide a sculpt.
Orthographic Views: Orthographic (ortho) views are two-dimensional drawings used to represent or describe a three-dimensional object. The ortho views represent the exact shape of an object seen from one side at a time as you are looking perpendicularly to it without showing any depth to the object.
Detail Exploration: What kind of buckles are on this character? What kind of Stitching? What kind of tiles are on the floor? etc. Anything that can be determined at this phase is much cheaper to do in concept than change later in 3d.
Material Definition: What kind of leather, Metal, Rubber is used. What kind of weathering is on these materials?
Accurate Perspective: Either you have developed great drafting skills or are using 3d as a perspective guide. Accurate perspective drawing is very helpful.
Will it work in 3d?: As a concept artist you need to think in 3d terms. A 3d artist will have to make what you are drawing. Will your joints move? Will that helmet shape work in the round? Will those shoulder pads decapitate the character? Etc. Answer these questions in your concept and your 3d counterparts will love you.
Clarity of Detail: When a 3d artist looks at your concept they should be able to know how they will go about building each shape. This ties in to accurate perspective in a way but also your rendering and line choices. One common example is tightly rendering the "juicy" parts of the concept then letting the feet dissolve into loose blotches. The 3d artist doesn't have the option to let some parts go - everything has to be fully realised in 3d - so too should it be in 2d.
*Tip from Dado Almeida - As seen HERE in this image by Dado - He is sketching wireframes over the concept to show the volumes better. This is some next level clear communication and something a 3d artist would immediately understand.
*Tip from Pior - Try Employing shading language when defining your materials. AKA Material Coding. This is a legacy of the tighter restriction of Anime where they needed to define materials across the entire production. Conscious shading decisions were made so that worlds chrome or painted metal looked consistent throughout the film.
Example 1 notice the difference in the rubber/chrome/painted metals all have different highlight and shadow tweaks to communicate the differences to the viewer.
Example 2 A more realistic example can be found in the great work of Range Murata
Any other ideas? As a 3d artist what questions do you want answered in a piece of concept art?