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How would you replicate this hillshade effect

- - - - - hillshade reflief shaded

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#1
Andrew

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Hi,

 

Been a while since I posted on here, was fun reading all the good content that I had missed. 

 

I see there are a few posts recently relating to Shaded Relief, Hillshading etc, but I feel my question is slightly different. I am not looking to do any tinting, or displaying elevation bands but I am looking to overlay a crude land type classification like in the topo shown in the link below.

 

https://www.dropbox....ington.jpg?dl=0

 

What I like about the topo is that the non veg/tree covered areas are just shown as white, but you can still see the terrain shading in the white areas and the white is still vibrant! How did they achieve this?

 

I'm using QGIS but have access to Photoshop if needed. Just for background my current technique has been to create three hillshades (azimuth 315, 15, 270) and combine them with vary transparency. I then apply my white non veg/tree areas ontop of this but I get a washed out dull white :(

 

Any tips would be greatly appreciated.



#2
tangnar

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Have you tried using Blend Modes in QGIS? This was generally done in graphics programs in the past, but the latest versions of QGIS have blend modes which is really nice. Blend modes help in blending layers together rather than just using transparency. 



#3
David Medeiros

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As tangnar124 suggests, this is the result of layer overlays with shadows on one layer and land class colors on another. A simple overlay with transparency will work, but for full control and to preserve the vibrant white sections you'll probably still need to process in something like PS. Most hill-shades, even ones that are shadows only, no hypso colors, will have a somewhat grey background. You can use levels or curves in PS to pull those greys out of the image, giving you a fully white background but preserving most of the shadows. Then overlay this with the color layer for the land class and set transparency to something like multiply, or linear burn.


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#4
Andrew

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Thanks Tangnar123. I have tried the blend modes in QGIS using a white overlay the softlight blend mode gives me the best result, it just doesn't seem 100% the same.

 

Has anyone made a similar topo map that can tell me exactly how they achieved it? It doesn't matter if you used different software to what i'm using, i'm just curious to know how its done.



#5
David Medeiros

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Thanks Tangnar123. I have tried the blend modes in QGIS using a white overlay the softlight blend mode gives me the best result, it just doesn't seem 100% the same.

 

Has anyone made a similar topo map that can tell me exactly how they achieved it? It doesn't matter if you used different software to what i'm using, i'm just curious to know how its done.

 

See my note above for the general workflow. I use Natural Scene Designer to get a "white" hillshade which is supposed to be the shadows only, no background color. I process this in Photoshop to remove the slightly grey background pixels giving me a a true shadows only image. Everything else is pure white (or pure transparent). I then add a new layer to the same file in PS that contains the veg colors (or in my case usually a land elevation colors layer, a terrain texture layer, and terrain smoother layer). Use PS layer transparencies (usually multiply or linear burn) to add the layers together while preserving the white. I'm probably forgetting something but thats the gist of it.


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#6
tangnar

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I think David is right, you are layering things correctly but you still have those grays that you need to remove so you just get the shadows. Is that the issue? As a quick example, I just made some adjustments to a shaded relief in QGIS using the contrast, brightness, and transparency settings. The white areas are not a part of the land cover, they are just blank and reveal the white on the shaded relief. 

 

example.jpg



#7
David Medeiros

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Great example shots. It may be obvious to those of use who do this a lot, but it's probably worth mentioning for novices; layering white over any other colors in a GIS or PS will not give you white in those areas with a transparency effect on. The white is an absence of any other pixels on the combined layers, not a white overlay. Hope all this helps.


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#8
Andrew

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Thanks guys






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