Relief Shading Options

[E.LeFevre]

Hi,
I'm sure most of you are familiar with the website www.reliefshading.com. I've been trying to shade the contour map in the "try it" section using the air brush tool (Photoshop) set at different widths and level of transparency. If you dont know what I'm referring to, follow this link and check it out. It's a lot of fun.
View the link here:

Has anyone had any success in shading this map with Photoshop (or any other photo program)? It's very difficult. Any suggestions on the tools, settings, and techniques you used would be great. If you have not tried it yet, you should.

[Hans van der Maa...]

Do you use a tablet for this, or just the mouse?

Personally, I'm left-handed, but I use my mouse with my right hand. For normal mousing that's no problem, but the specific motions needed for this kind of work are very difficult to do with my 'wrong' hand.

[Lui]

Hi, Erin,

I'm doing a lot of hillshading with Photoshop (10-20 map sheets per year). But I draw so called manual enhanced analytical hillshading. So basically I compute analyitical hillshading and then generallize, adjust and correct it.
I would suggest that first you draw a layer of very generalized soft shading using airbrush with low opacity (20% or less) and fade out setting. Then you may draw a more detailed and sharper hillshading with smaller brushes. The final step would be fine hillshading, ridge and waterflow adjustment. For this purpose I'm using a smudge tool. Finally you may want to do some areial perspective correction with contrast and brightness adjustment layer driven by height (elevation) data.
Using a pressure sensitive input device (tablet) you can create a nice looking (even Swiss style) hillshadnig.
Now I'm doing hillshading for 4 years and I must admit that in the first year ot two I didn't produce visualy very pleasant hillshading. It takes some time to find out appropriate technic for hillshading and most importantlly I have to learn what are the most important elements of hillshading.

If you din't find yet, you would like to see a tutorials at Tom Patterson Shaded relief page.

Just my 2 cents.

Lui

[Hans van der Maa...]

Lui,

How much time do you spend on an average map sheet?

[Lui]

Well it depends on relief structure and complexity. In mountain region with sharp and recognizable relief structures I spend about two weeks per sheet (54×46cm). In karst region I can spend even more time due to difficult relief recognition and complex terrain morphology. Unfortunatlly Slovenia (where I live and work) has a lot of karst, even the name karst came from one of slovenian region named Karst - Kras. For other sheets where terrain is more simple I spend one week for hillshading.
Anyway, the time that I spend for hillshading is more dependent on hillshade quality and detail than anything else. During those four hillshading years I learned how to produce faster and better hillshading for different types of terrain. Well sometimes I'm still a little bit confused when I see a mountain terrain with karst features.

@Hans van der Maarel
I think that using a tablet is a must if you wish to create smooth gradients.

Lui

[E.LeFevre]

Lui,

Thanks for the reply. I've taken your advice and started with a generalized shade of around 20% transparency and a larger brush, and then I am going back and adding in the finer details with a smaller brush. My shading job looks absolutely terrible, but it's a huge improvement over my initial effort.

Question: do you start a hillshading project (photoshop) by shading in a large section at a time, or do you complete small sections and then move on? Where do you begin? It seems like the only way to keep shading consistent is to apply a generalized shade over the entire area at once, and then "remove" or "add" shading depending on the terrain. It seems difficult to match a "base" shade when the pressure of the brush varies. Anyways, thanks for your help.

You should consider creating and posting a tutorial on basic hillshading. I'm sure everyone would love you for it. Consider also posting some of your work. Thanks again, Lui. Also, thanks for the link! Erin

[Lui]

Erin,

you suggested very interesting way to create handmade (well, penmade) hillshading! To create hillshades from scratch (without analytical hillshading) you can try to fill whole area with so called neutral gray. This gray would present a flat areas so the value could be between 5-25% depending on hillshade usage. I'm usually aming for 12-15% for separate hillshading plate. When the whole area is filled (with shift-F5 in Photoshop this is lightning fast) you can use pen tool or even a burn and dogde tool with large and smooth brush to add or remove gray tone. Try to use elevation dependent brush sizes: for lower parts of a map - larger and smoothed brushes and for higher parts - smaller and more direct brushes. You can even lower your opacity brush settings from 20% to 10% to achieve more smoothed gradients. Patience is one of the most important quality of hillshading artist the other one is experience. Better using more subtile strokes than less but more aggresive ones.

My hillshading workflow:
- create DEM from countours, breaklines, spot heights,...
- analytical hillshading with different light azimuths
- hillshade merging
- manual hillshade enhacement
- - smoothing (mediana,...)
- - hillshade generalization (darken, lighten)
- - local hillshade adjustment and generalization (the most time consuming process)
- - lightening of flat areas
- - applying areial perspective (with grayscale height map)
- - ramp down maximum grayscale values (for separate hillshading plate)

I always begin to enhance a hillshading at upper left corner following terrain features. I have dual monitor setup (2×1600×1200) in Photoshop using one monitor for overwiev (10-25% zoom) and the other for working (100% zoom). Both monitors are regularly color callibrated. I'm also using Wacom Intuos 2 A4 tablet.
And that's it.

Oh, and you can post your hillshading efforts. I will try to post some of my work when I'll have some time. I promise.

Nice day with a lot of sun that cast nice subtile shades

Lui

[Martin Gamache]

Try to use elevation dependent brush sizes: for lower parts of a map - larger and smoothed brushes and for higher parts - smaller and more direct brushes.

Erin,

In adition to Lui's excellent methodology I would suggest adjusting your brush size and the detailing of your shading to slope angle and terrain complexity. I often generate both aspect images and a slope images to manipulate highlight colors and to garner some more ideas of the terrain. Using masks made from these images you can add highlights to different aspect slopes in combination with lowlands and flatlands fairly easily. Additionally I'll use satellite imagery and orthophotos to look at the actual terrain to better understand what it looks like. Contours alone (depending on the scale, interval and quality of the photogrametry) rarely are enough.

Tom Patterson's excellent tutorials are worth re-reading as well. He often describes problems with analytical shading such as innapropriateness of the shading to the scale at which it is depicted. Now that relief shading is available at the touch of a button, it seems that everyone is using it. Unfortunately few people take the time to actually make it look good the way Lui describes. Having a good eye for what level of detail looks good at what scale is crucial.

I will try to post the shading chapter in Imhof's book in the coming days as it really goes into alot of details about these things. The way shading looks also depends on how it will be combined with vector data if at all. Too often it seems shading is beeing done with a hammer approach that is completely overwhelming.

mg