www.photomacrography.net :: View topic - hillshade
www.photomacrography.net Forum Index
An online community dedicated to the practices of photomacrography, close-up and macro photography, and photomicrography.
Photomacrography Front Page Amateurmicrography Front Page
Old Forums/Galleries
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
hillshade

 
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Macro and Micro Technique and Technical Discussions
View previous topic :: View next topic  
Author Message
iconoclastica



Joined: 25 Jun 2016
Posts: 262
Location: Wageningen, Gelderland

PostPosted: Fri May 22, 2020 7:30 am    Post subject: hillshade Reply with quote

I was intrigued with Lou's suggestion to apply hill shade to the depth map and decided to try this a few times. So far, my experience is not that it reveals all kind of extra detail, but I think it is another tool to use in the post. And perhaps results may be further improved.

Here is an example**) of where it worked quite well. This is an (increasingly drying) utricle of Carex arenaria. The surface bears a number of shallow length ribs that are quite hard to see in this stage.



Here's the depth map. Note that the stack consists of 30 steps, so terraces are notable:



From this it's an easy step in ImageJ to produce the hill shade:



My depth maps always are rather rough and full of pits or spikes. I guess those are interpolated areas where the sharpest layer could not be determined. Using the hill shaded map like this would result in a very warty image, therefore I blurred the HS before applying it to the image.
Here the result is blended with overlay 100%, which does not look good, but clearly shows the combined result:



Changing the blending mode to soft-light looks better:



The ribs are more distinct now and the wings left and right of the neck look flatter.

Wim


**) This 30-photo stack was not shot for this purpose but to see if the 10x mitutoyo could act as c. 5x objective for these 3-5mm subjects by stacking it with the Canon 70-200/4
_________________
--- felix filicis ---
Back to top
View user's profile Send private message
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 20650
Location: Richland, Washington State, USA

PostPosted: Fri May 22, 2020 9:17 am    Post subject: Re: hillshade Reply with quote

This looks like a very useful technique. Thanks for the investigation!

iconoclastica wrote:
My depth maps always are rather rough and full of pits or spikes. I guess those are interpolated areas where the sharpest layer could not be determined.

Pits and spikes definitely occur where the sharpest layer could not be determined. But regarding interpolation, it's the other way around: pits and spikes occur in non-interpolated areas. Interpolated areas -- the ones that go "black in preview" in Zerene Stacker -- will err on the side of unrealistic smoothness.

--Rik
Back to top
View user's profile Send private message Visit poster's website
Lou Jost



Joined: 04 Sep 2015
Posts: 4268
Location: Ecuador

PostPosted: Fri May 22, 2020 10:55 am    Post subject: Reply with quote

Thanks very much for testing my idea! It may only be practical for surfaces that have no overlaps, like the complex leaf surfaces that I am currently working on. These surfaces have steep mountains and valleys and craters, but no overlapping elements. They look just like miniature mountain ranges, which is what gave me the idea. Epi lighting gives nice uniform illumination to all parts, and if shadows could be applied in post, it would result in better detail and less noise(especially in areas where you want to have shadows) than one would be able to get with undiffused lighting that produces real shadows.

And of course the ability to experiment with the light direction and quality AFTER taking the stack is a big advantage.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com
Back to top
View user's profile Send private message Visit poster's website
iconoclastica



Joined: 25 Jun 2016
Posts: 262
Location: Wageningen, Gelderland

PostPosted: Sat May 23, 2020 6:19 am    Post subject: Reply with quote

Here's a more realistic example (Equisetum variegatum), the same that if have used previously with another technique. Here, the HS brings out the surface details more pronounced and actually reveals details that I couldn't distinguish before.

Here's the stacked image:



Its depthmap is cleaner than the one above and therefore its HS too. I now applied only 3 pixels gaussian blur (30 in the example above):



And here's the result (original, again, at the left). I have outlined areas with new detail. The small particles are sand or dust, but the rectangular area contains meaningfull detail:


_________________
--- felix filicis ---
Back to top
View user's profile Send private message
Lou Jost



Joined: 04 Sep 2015
Posts: 4268
Location: Ecuador

PostPosted: Sat May 23, 2020 6:23 am    Post subject: Reply with quote

Nice! It would be really interesting if you had an epi-lighting original with no shadows. Then you could adjust the hillshading to completely control the locations of the shadows. You could choose the direction that gave the best result.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com
Back to top
View user's profile Send private message Visit poster's website
iconoclastica



Joined: 25 Jun 2016
Posts: 262
Location: Wageningen, Gelderland

PostPosted: Sat May 23, 2020 7:29 am    Post subject: Reply with quote

Lou Jost wrote:
Nice! It would be really interesting if you had an epi-lighting original with no shadows. Then you could adjust the hillshading to completely control the locations of the shadows. You could choose the direction that gave the best result.


With truly flat lighting surface details become almost indiscernable. Such originals I don't have, quite the opposite indeed, but it can be simulated in photoshop by removing the luminosity information and only leave a colour layer. Then add the HS in blending mode luminosity (OK, that first step is not necessary unless you want to see it):


original | colour only | added Hillshade

It is definitely not the same, e.g. all luster has gone, which is surface information too. In fact it is much like a SEM-image. But when you're interested in the topography, it could be an interesting artifact in itself.
_________________
--- felix filicis ---
Back to top
View user's profile Send private message
Lou Jost



Joined: 04 Sep 2015
Posts: 4268
Location: Ecuador

PostPosted: Sat May 23, 2020 7:57 am    Post subject: Reply with quote

That's a very interesting idea. I jiust downloaded ImageJ and will try to play with this on my epi "leaf landscape" images.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com
Back to top
View user's profile Send private message Visit poster's website
Lou Jost



Joined: 04 Sep 2015
Posts: 4268
Location: Ecuador

PostPosted: Sat May 23, 2020 8:02 am    Post subject: Reply with quote

The highlights, especially the leftmost band of bright highlights, show fine ridges and valleys that appear flat on the hillshaded image. Maybe your depth map smoothing did that, even though it was only 3 pixels?
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com
Back to top
View user's profile Send private message Visit poster's website
iconoclastica



Joined: 25 Jun 2016
Posts: 262
Location: Wageningen, Gelderland

PostPosted: Sat May 23, 2020 12:06 pm    Post subject: Reply with quote

Lou Jost wrote:
The highlights, especially the leftmost band of bright highlights, show fine ridges and valleys that appear flat on the hillshaded image. Maybe your depth map smoothing did that, even though it was only 3 pixels?

That, and also that the altitudinal variation there is not greater than the step size (assuming we are looking at the same area).

I think the hillshade algorithm expects a regular raster of a continuous (floating point) variable. Our depthmap steps integer steps and then needs an interpolating function to estimate the slopes and with that the intermediate values.
_________________
--- felix filicis ---
Back to top
View user's profile Send private message
Lou Jost



Joined: 04 Sep 2015
Posts: 4268
Location: Ecuador

PostPosted: Sat May 23, 2020 12:14 pm    Post subject: Reply with quote

We might have to use smaller step sizes than normal when using this technique.
_________________
Lou Jost
www.ecomingafoundation.wordpress.com
www.loujost.com
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Macro and Micro Technique and Technical Discussions All times are GMT - 7 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group