greyscale values in Photoshop 6.0

[ldvger]

Ok, I have found what I think is enough information elsewhere to maybe take a stab at creating a grey scale map by tracing over a USGS map, but have a new issue I am hoping someone may be able to help me with. 

I have been given definitive RGB values that coincide with how the game reads those values to terrain elevations as follows:

RGB=0: 252m below sea level
RGB=50: 102m below sea level
RGB=84: sea level
RGB=100: 48m abv sea level
RGB=150: 198m abv sea level
RGB=200: 348m abv sea level
RGB=255: 513m abv sea level

This is without any height mod installed.  These values were established by Mallowthecloud.

Problem is, there are many ways to arrive at any of the RGB values given above.  I could set sea level to be red 84, green 0, and blue 0.  Or any other combination of numbers that total to 84.  Will any combination of numbers give me the same RGB gray scale value?  If I set red at 84, green at 0 and blue at zero, will that give me the same grey scale RGB value as setting red at 0, green at 84, and blue at zero? 

Because my version of photoshop doesn't allow me to just pick an RGB value from a list or a chart of colors....it provides me with a dialog square that is multi-colored which I can click on to pick a color...and it provides me with dialog boxes that ask me to enter absolute values for R, G, and B, as well as hue and saturation.  Quite frankly, I'm a little lost as to how to select a given RGB value under the circumstances.

Can anyone help?

Lora/LD

[Bobbi]

You must change the mode from RGB to Greyscale.

Please open "Image" menu ,and then click "Mode" ,and finally click "Greyscale"
PS:My Photoshop isn't English,maybe it isn't right.

In Greyscale Mode ,you can only set your greyscale value, not RGB value.

[ldvger]

Bobbi-

If I change the mode of the image from RGB to geyscale, how then do I correlate the RGB values I have for elevations to grey scale values? 

Besides which, I should be able to draw in color and convert to greyscale afterwards. 

I don't have any grey scale values for corresponding elevations in game, all I have are the RGB values listed above.  Following the tutorials over on ST, the USGS maps are downloaded as RGB TIFF formats, adjusted in RGB format, THEN turned into grey scales. 

I really do appreciate your trying to help me solve this issue, but truth is I am kinda stuck for the time being with the only info I have...and that happens to be RGB values. 

I don't know enough about graphic programs to know if the RGB values I have will work in grey scale regardless of the individual r,g, and b values assigned.  I mean sea level of RGB 84 could be comprised hundereds of ways...will they all translate into grey scale exactly the same?  I have no way of knowing.  This is what I am trying to discover. 

Lora/LD

[homefryes]

Hi, Lora --

What I did for my map was set all three RGB values to the same number. So for sea level, R=84, G=84, B=84. I used identical numbers for each level, so there is no "color" other than grey. Then when saving it, I told the program that it's a greyscale image. In doing so, I am then able to upload it into SimCity. I'm not at all certain, but my gut feeling is that R=84, G=0, B=0 is NOT going to net the same result as setting all three values to 84 once you tell it to be greyscale; I think yours will be darker than a grey=84 value.

Furthermore, as I'm creating a map, I'll usually work on the highest elevations first, and then work my way down, sending each subsequent layer to the back behind the previous layers as I go along. I hope this is helpful.

-- Don

[ldvger]

What I did for my map was set all three RGB values to the same number. So for sea level, R=84, G=84, B=84. I used identical numbers for each level, so there is no "color" other than grey. Then when saving it, I told the program that it's a greyscale image. In doing so, I am then able to upload it into SimCity. I'm not at all certain, but my gut feeling is that R=84, G=0, B=0 is NOT going to net the same result as setting all three values to 84 once you tell it to be greyscale; I think yours will be darker than a grey=84 value.

Don-

That is so simple and makes so much sense it's almost scary.  Makes me want to slep myself in the center of my forehaed and say "Why didn't *I* think of that".  Sheesh!

Furthermore, as I'm creating a map, I'll usually work on the highest elevations first, and then work my way down, sending each subsequent layer to the back behind the previous layers as I go along. I hope this is helpful.

I was kinda wondering about this, too...actual method.  My plan was to start at sea level and work my way up, putting each contour on a different layer and use the RGB color for that elevation.  For instance, trace the shoreline with RGB 84, then trace the 100' contour line on a second layer with RGB 100 (if that's what it is, I have yet to extrapolate the actual RGB values I'll need to use).  I was planning to trace all the contours first, then use the fill tool with two layers at a time turned on (sudden thought: will Photoshop let me have two layers turned on at the same time?) to fill the spaces between contour lines with the appropriate RGB value color.  But...maybe your on to a better technique starting at the top and working down, filling each layer at a time.  If your method works, and it seems it does, I might as well use it and save myself the bizillions of hours experimenting with my method would take. 

Thanks a bunch, your info helps me a lot!

Lora/LD

[homefryes]

Lora, you're quite welcome. Let me also suggest, though, that you give some depth to your ocean/sea/lake (whatever it is). In other words, give it contours as well, working your way lower from RGB=84. You might have already considered that, but wanted to throw that out there, in case you hadn't.

-- Don

[ldvger]

Don-

Well, as a matter of fact, given that the topo map I am tracing includes underwater topos as well as above sea level topos, yeah, I had considered creating underwater depth to my ocean areas.  In fact, in another post on a similar topic over on ST, where I learned the RGB values for various elevations, I asked if underwater contours could be created using negative RGB values (I know, that seems really dumb, now...that's how much I've learned about creating grey scales in the past week or so). 

Thing is, I think the underwater topos are in fathoms rather than feet, which adds another layer of math to my extrapolations, but I like math, so no big deal. 

The next big headache I have is finding the highest point on my map and assigning that the highest RGB value of 255, then working my way downwards from there.  I may end up with my sea level below RGB=84, but I can use Terraformer to "lower Terrain".  I ended up having to do that with my current region, which heblem made for me.  Someone also suggested installing a height mod to compress the RGB values and thus allow me heights greater than 1142' (which is game max at RGB=255), but I'm not sure how to use a height mod and again it would add yet another layer of math into the mix. 

So many options!

Lora/LD

[SeanSC4]

Will Photoshop let me have two layers turned on at the same time?

Yes, PS allows you to have an arbitrary number of layers visible. The area you are editing is solely based on which layer you currently have selected. This allows you to have layers visible for reference while you drawn within a new or existing layer.

I use RGB mode exclusively and never convert it back to greyscale prior to saving. When choosing a "height", you merely need to set all three RGB values to the same value. This allows you to have additional adjustment layers like gradient maps and posterize or to use the blending options of additional layers to mask certain values in a particular color (for instance to show where the water table is). Any layers that show up as color merely need to be turned off prior to saving a jpeg that will be used for importing into SC4.

I could probably write five pages on how one can use layers within PS to construct greymaps for use in SC4.

[dobdriver]

Lora G'day,

To find out what greyscales equal you

1.make a 64 x 64 pixel image in grey and the paint it with say 30% grey
2.make a 1 x 1 pixel red config.bmp and put it in your region directory
3.open terraformer and open the 1 pixel region then load the 1 city tile
4.run the cursor over the map and read the height.
5.write the height 30 = ? in a txt file
6.re-paint your map lighter if under water or darker if above then reload in terra


You will soon discover what grey value equals water, 100m, 200m etc

Personally I have one in hex for 16bit 10m above to 10m below sea level in 100mm increments.

Cheers
dobdriver