synesthetic heightmap from image

[johnvanvliet]

a synesthetic heightmap from image

" easier said then done "

-----------------

first the disclaimer

there is NO "great" or "set" way to convert a image into a heightmap !

second

EVERY image is going to be a bit different !

and depending on the starting point different ways / tools can be used

a black and white copy of a SHADED RELIEF MAP IS NOT !!! a HeightMap

heightmaps are the Z axis in a x,y,z 3d coordinates
in this case the distance away from the center of a planet


this is from a question i was asked
how to convert this painted map ,using copy/past and the clone tool and painting into a HeightMap


first thing is LOOK and i mean really look at the image

because you will need to make masks ( i used to do this in the photo Darkroom and using a computer is WAY!!!! easier )

first one is a ocean & lakes mask
the second is the WATER mask ( ocean .lakes, and RIVERS )

then a mask for just mountains
and if needed one for just low rolling hills


the more masks and using small areas the better the quality and MORE TIME needed so for this i am using just the basics
and all FREE GPL'ed software that can be used on ( or free and using WINE)
Linux
Apple
And
Microsoft Windows

Gimp and the G'Mic plugin
gimp 2.8.4 will make a 8bit heightmap
Gimp 2.9.4 DEVELOPMENT ( will be gimp 2.10) can make a 16 or 32 bit heightmap

and the plugin for Gmic

" select by color" is a great tool for SOME images
both "connected area" and "all image" tools can be used

for others the gmic plugin tool "Repair / Local similarity mask" can be used



other useful tools are the Gmic

"Contours / Curvature"
"Contours / Distance Transform"
"Contours / Isophotes "



you need to get clues from the image in question

for this one the desert area in the mountain ring looks to be a bit higher than the land around it


and most of the rivers are LIGHT brown for a mask these need to be darker than the green area

making masks can take some time

[johnvanvliet]

once the masks are done i use a combination of "distance transform" and "plasma noise"
on masks and images to synthetically make a heightmap

open the ocean mask in gimp
in layers duplicate it




select the upper layer and in the gmic menu select "rendering / plasma"
the default values will do



then click the "eye symbol" to hide that layer and select the lower layer
and invert the color of the lower image layer

and use the Gmic tool
"contours / distance transform"

set "value" to 255
set "metric" to Euclidean
set "normalization" to normalize

then blend the two layers by setting the upper to "50%" transparent
and "merge down"
then lower the contrast a bit




open the "ocean" mask again and copy/past it on to the current image
( or make 3 layers but if the image is BIG this will take time and RAM!!!)
set this layer to "darken only"




now mix the ocean and lake and rivers masks using "darken only" on the layers and repeat the plasma and distance from above




do some dodging and burning ( i like to use one of the "bush" brushes and for this set to 120 pixels
and blend these two images

this is the base for the land


now this map has VERY LOW shaded relief shadows ( some will have MAJOR shadows and you will NOT be able to use this "cheat"

-- NOTE!!!!
this uses the terminal version of G'Mic and it dose work using MS's "cmd.exe" )

gmic 4k.posterlarge.png --split_freq 0.06% -n[2] 1,255 -o[2] hi.pgm

open in gimp and paste the mask layers as "darken only"
and after applying the masks




this makes a image of just the VERY high frequency data in the image
mainly the white mountain tops ( this is a CHEAT)

dodge some of the mountain area





now duplicate the layer and add a 13px blur and set the top layer to "grain merge"
repeat with 21 px blur "grain merge"
and 31 pixels "grain merge"

then a few duplicate / blur/ BUT LIGHTEN ONLY on the layers

adjust the gama point so that the low areas are a bit darker
( 0.8 ot 0.6 should do)



-- like i said this is a CHEAT do to the very low amount of shadows !!!!!

now blend the two
the "noise and distance " with the highpass above
then "normalize
( color / auto / normalize )

this stretches the tones to 0 to 255


time for wilbur

[johnvanvliet]

For Wilbur i like to use the 32 bit BT format

resave the base map as a 32bit floating point
gmic and Nip2 can do this just fine

use GDAL to convert to bt

gdal_translate -of bt  basemap.tiff WilburInput.bt

run a few Cycles of precipitation based erosion and incise flow

and export to bt
( 32 bit has + and - pixel values )

and use gdal to convert to a 32 bit tiff



and a 8 bit normalized copy of the float





for lower coastal area drop the GAMA to say 0.6
then run through wilbur

shaded using the gimp "bumpmap" shader and a 8 bit copy of the heightmap




.

[ranger]

WOW thank you soo much!!

[ranger]

what is this coverting to 32 bit thing etc

[johnvanvliet]

see:
https://en.wikipedia.org/wiki/Image_file_formats

a everyday red green blue digital image is 3 8 bit images
each layer has pixel values form 0 to 255

a 16 bit per layer image has values 0 to 65535
a SIGNED 16 bit per layer image has values-32768 to +32767

a single precision float has ( 2 to the power of 31 minus 1 ) numbers
2³¹ − 1 = 2,147,483,647

and can be positave or negitave values

tiff and OpenEXR are two 32 bit / layer image formats
and so is the "vips" format i use a lot

most DEM's ( height maps) are signed 16 bit data
tiff sort of handles this as a 32 bit float ( it is a ancent image format after all -- but VERY handy for height data

[CharlieP]

I love this synthesis of GIS tools/thinking and image manipulation!

Awesome stuff, thanks for sharing John, I'm glad I found this.

[skymandr]

I love this synthesis of GIS tools/thinking and image manipulation!

[Jeffmaster223]

Hey John, loved the tutorial.

But i'd love to see a tutorial on how you made this:
http://imgbox.com/SAe04IkP

I love how it looks like it was on Google Earth. Could you suggest (or make) a tutorial on that? Thanks.

[ranger]

Hey John, loved the tutorial.

But i'd love to see a tutorial on how you made this:
http://imgbox.com/SAe04IkP

I love how it looks like it was on Google Earth. Could you suggest (or make) a tutorial on that? Thanks.

I was the one that made this wanting help to make a height map hah!! I actually have a tutorial on how to make this style.