5 replies to this topic

[Hans van der Maarel]

I've been working on a personal project for the past few months. Well, it would have gone faster if I wouldn't have been so darn busy, so for all I know this may turn into a 5-year plan

Anyway, it's going to be a topographic map of the Mount St Helens area, combining a hillshade with contour lines, road and hydro vectors and text labels. I'm planning to have this printed as a poster and use it as a self-promotional thing.

I would like to ask your opinion on the hillshade first. After reading through the Imhof book and seeing what he did with highlighting the sunny slopes, I figured I'd give that a try. So I set up a VNS project and made a few renders, some with the sun coming in from the northwest, others with the sun coming in from the souteast and after combining them in Photoshop (along with a layer of land-use) I got this result:

 option_1.jpg   290.1K   204 downloads

The sunny-slope thing is seen in the yellowish tint on the northwest facing slopes. It also very nicely highlights landscape forms on the nw side.

However, I've been trying my hand on some manual edits as well and came up with this:

 option_2.jpg   277.21K   158 downloads

So what are your thoughts? Am I on the right track with this? I kinda like the first option, especially because it doesn't take as much time to do properly (although rendering the whole scene twice in VNS obviously is a drag and combining all the layers in Photoshop and set all the blending modes and transparencies right is tricky too)

[BEAVER]

I think that the yellow tint is too strong in both images. It's very confusing and if didn't know that it's supposed to be sun shining down on the slopes, one would think that's dirty snow or some other land cover. I'm not too crazy about both shadings. Sorry.

[Charles Syrett]

Yum. Looks wonderful so far.

I'm not sure what VNS is. (The acronym finder I used didn't send up any cartographic references!) What software did you use for the original rendering? What about the various parameters? You know....gradient method (Central Difference, Midpoint difference); vertical light settings; shading methods (Peucker's, Lambertian, Lommel-Seeliger)....come on, give us the gory details!!

It looks like you're losing detail of the NW slopes. Can you try setting up a layer that shows just that area in more detail (using different settings), and then using various Photoshop tools to get a visual "match" to the rest of the drawing?

Imhof was using strictly manual methods, mostly with pencil. To emulate his approach you have to feel very free to alter / edit the original imagery. You've been doing that to some degree, but I think you have to allow yourself even more creative license here.

Somehow the "sunny-slope thing is seen in the yellowish tint" looks more like some kind of land cover than a lighting effect....at least to me. Same with the manual edits....it still doesn't look like lighting. Maybe you should start with just the relief modeling in grayscale, get it looking right vis-a-vis lighting etc, and then work in the land cover afterward.

Since you don't have client pressure on this, you should be able to mess with it to your heart's content and come up with the ultimate mountain relief map!

Charles Syrett
Map Graphics
http://www.mapgraphics.com

[Adam Wilbert]

I would agree that the yellow tint is too strong and the abrupt edge causes it to look like a land cover classification, not a piece of the hillshade. I practically live by Tom Patterson's tutorial on illumination and would recommend it to anyone. It produces nicely blended highlight tints that add warmth to the hillshade, without being overtly "yellow". The other component is creating a blue/purple shadow tint layer on opposing slopes to balance the color cast.

I'm not familiar with VNS (Visual Nature Studio for Charles ) but having worked with other 3D modeling programs, I would suggest maybe trying to do it in one render by setting up several different light sources of different tints and intensities. Would it be possible to set up multiple "sun" lights of different colors and light your model as if it were actually a physical object in a studio setting using theater gels?

[Hans van der Maarel]

Adam,

Yes, that's possible in VNS. You can set up multiple light sources. In this case I had actually set up a "regular" and a "counter" sun and rendered separate images to be combined in Photoshop later on. It is possible to do it all in one pass, but I think Photoshop offers more options to get the mix just right. Still, it's worth trying out in VNS.

On a side note, if all goes well I'll be doing a presentation on VNS at this year's PCD.

This is an intermediate trial. I've added the yellow layer from the first image but turned it into greyscale to show the detail in the NW-facing slopes that tends to get washed out in NW-lit renders. I erased the light parts from this greyscale layer (i.e. the SE-facing slopes) so it wouldn't affect the 'normal' shading too much.

 option_3.jpg   267.38K   115 downloads

Haven't got the hang of masking layers yet, but that would be something to try.

Charles,

Indeed, this is something of a hobby thing where I can try out different options without the pressure of needing to finish something (or having to do it in a certain way because that's what the client is paying for).

[FlatEarth]

Hi,

I've been messing around with curvature to highlight ridges and darken valleys. I've tried not using black for shadow as it can make things look dirty rather than in shadow.

Sorry I couldn't get the picture uploading to work.


Cheers,