19 replies to this topic

[Hans van der Maarel]

Let me know your thoughts on this. I want to kill the 315 degree rule, but don't want people to say my maps look inside out!

Unfortunately... they do look inside out. As Charles said, the 315 shading simply works. The only exception would be if you have subtle relief features oriented in that direction, so they wouldn't cast much of a shadow. In those cases you could add some local lighting.

[Crischan]

About the 315°-rule: It for sure mustn't be taken as a dogma. If your mountains face south-east to north-west you are lost with it for sure. Global or (more complex and time consuming) local adaptations are needed then, see http://www.reliefsha...tdirection.html and http://www.reliefsha...djustments.html
In general I don't belive reliefshading must depict a real image as produced by the sun in the landscape. It is a tool to transport an idea - the idea of how the landscape is formed. As long as it does so, I am happy with any "unnatural" methods. And in this way, Google's method isn't as worse as the standard method using default parameters implemented in ArcGIS or GRASS (which are the tools at my disposal) and is a good way to do extensive areas quickly.
Btw, the key is pretty much the high sun angle which makes flat areas almost white which is good for subsequent color blending and deemphasizes small bumps with small slope values. Another note: GRASS' default azimuth angle is 270 which most always look weird to me.

So I'd say there's a cheap (computingwise) way to mimic Google's shading for those who like it. And many more pleasing methods of different complexity. This is art and as art goes, taste differs.

[DaveB]

Sometimes things become standard because they work. It's still good to question these "standards" from time to time. That's how progress is made. (says a guy who loves antique maps and keeps trying to emulate the older styles! )
But not all change is good. It should be judged on whether ir works - does it convey the information you want it to convey? Does it look aesthetically pleasing? Does it help the map's audience?

[Malcolm RH]

I don't want to offend you, but.....

No offense taken Charles. And everyone else makes a good point: lighting from the NW is usually best.

I guess in my case I often feel the need to make an exception because I am trying to make points about vegetation, and really I should just inform my audience that radiation and realistic lighting is a thematic layer. What I often am trying to point out is that in high latitudes, the heat and light of south facing slopes allows the establishment of annual invasive species.

But maybe I can still do this with normal shading?:
 aldrprob2.jpg   96.96K   76 downloads
Sorry about the hideous color scheme, not what I normally use, but blue is poor habitat for our weed, red is good habitat for our weed.

In any case, google-style is really one of the simplest hillshade methods, and is probably great for general audience maps these days because everyone will instantly recognize it.
Plus, Google has made explaining what I do for work to people at parties much easier!

-Malcolm

[Matthew Hampton]

And now for my own unpopular opinion: I think Google's relief is awful. Just compare it with any well-done 315 relief shading. Google has reverted shaded relief portrayal to the 19th century

I respectfully offer an alternative opinion to yours Charles, and that MDOW shading is hardly reverting to 19th century portrayal, and in most cases is superior to a single-direction (e.g. 315 deg.) illumination. I think they have also done a decent job blending higher-resolution data with lower-res. Not that it's really effective to show LiDAR-derived shading at 1:200,000, I just think it's nice that it's blended-in where it's available.