http://gislounge.com/relief-shading/ Geographic Information Systems, Maps, GPS, and GIS Jobs Tue, 07 Feb 2012 16:13:11 +0000 hourly 1 http://wordpress.org/?v=3.3.1 http://gislounge.com/relief-shading/#comment-345 Mark Mon, 07 Apr 2008 16:51:22 +0000 http://gislounge.com/?p=710#comment-345 I've noticed that it seems common to hillshade with the sun emulated at 315° & 45° above the horizon (or something similar). This doesn't appear to be good practice relative to real sun angles in the northern hemisphere. I realize using actual figures for the basis of a primarily visual calculation could have downsides (things might literally 'appear' to be upside-down). Though this unrealistically illuminates cool northern slopes & shades exposed southern aspects. This is also in direct contrast (quite literally) to the realities of aerial imaging. One can imagine what a transparent overlay of the two would look like (not good). Do standards exist in this regard? Opinions anybody? I’ve noticed that it seems common to hillshade with the sun emulated at 315° & 45° above the horizon (or something similar). This doesn’t appear to be good practice relative to real sun angles in the northern hemisphere. I realize using actual figures for the basis of a primarily visual calculation could have downsides (things might literally ‘appear’ to be upside-down). Though this unrealistically illuminates cool northern slopes & shades exposed southern aspects. This is also in direct contrast (quite literally) to the realities of aerial imaging. One can imagine what a transparent overlay of the two would look like (not good). Do standards exist in this regard? Opinions anybody?

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