Our artist provides a picture indicating different height levels of terrain by color, how can I create a terrain by reference of it? I’ve create a raw file for this picture, but when I import this file by using “Terrain->Import Heightmap - Raw…”, I see nothing. Did I miss something?
Thanks.
I do that but not success. 
Shouldn’t be any issues with loading raw files, other than that the byte order might be swapped, so try “PC” instead of “Mac” or the other way around…doesn’t really matter as long as it imports.
–Eric
Creating a terrain from that needs 2 steps actually
You need to find an application that is able to create a smooth terrain heightmap from those terrase based map heights (if you imported that, you would get distinct heights, nothing smooth)
You then would import that newly generated heightmap
Thanks for reply.
Then how can this color picture be converted to the grayscale one in photoshop? Is there any option to choose the height of the terrain, and how to change it to the desired scale when imported into Unity?
Our artist only converted this color picture into grayscale one by default in photoshop, and the output raw file just can not be imported into Unity as expected, so maybe we miss something, at least there are options indicating the height of different colors.
To ensure that the most bottom of the terrain is black, the highest for the white, middle gray ladder.
Yes, in the Import Terrain dialog you get when importing a heightmap.
Can’t really say without seeing the file. You could always buy Fractscape. 
That will load pretty much any .png file as long as the width and height are the same (you don’t even have to convert it to grayscale) and make a nice heightmap that for sure will work in Unity. I cropped your pic square and loaded it in, and got this (on the left):
Note that the white part in your image should be black, which is why that part looks weird. White = highest, black = lowest. You can also smooth it out so it’s more natural and doesn’t look terraced, as you can see on the right.
–Eric
Fractscape is well worth the small investment even if you use it for one project. I recently needed to create a terrain based on some scientific charts and data. I couldn’t decide how I was going to do it until I remembered I had Fractscape on my HD. Fractscape made the whole thing as easy as child’s play, and the ability to tweak the transitions in elevation and textures was excellent.
Thanks guys, I got one and it works well. Hope Unity has such a module. 