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Friday, 5 March 2021 Dereel Images for 5 March 2021
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Finally: the garden
Topic: gardening Link here

Nathan and Brian, the gardeners, along round 8:30 this morning and set to to tidy up the garden with some pretty heavy-duty equipment:


https://lemis.nyc3.digitaloceanspaces.com/grog/Photos/20210305/big/Lawn-mower.jpeg
Image title: Lawn mower          Dimensions:          5184 x 3890, 3468 kB
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They had planned to mow the lawn and get rid of all the weeds, exactly what I had asked of Paul Gallagher five months ago.

They weren't completely successful:

 
https://lemis.nyc3.digitaloceanspaces.com/grog/Photos/20210306/small/garden-nw-2.jpeg
Image title: garden nw 2
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But then, I hadn't expected them to be. They'll be back on Monday to finish things off, if they can make it then. At least the place looks a lot tidier, though of course the shorter grass isn't as green as what we had before.


Fisheye or rectilinear?
Topic: photography, opinion Link here

Reading a message about fisheye or “normal” projections on the Hugin user group today. He wanted to convert a “normal image” to “fisheye image” using Hugin.

Is that hard? I had some recollection that you needed at least two images to do anything, but some checking showed that I didn't. Take a rectilinear image taken with the M.Zuiko DIGITAL ED 7-14 mm f/2.8 PRO at 7 mm, set output to “fisheye”, and stitch:

 
https://lemis.nyc3.digitaloceanspaces.com/grog/Photos/20190701/small/Sovereign-Hill-1.jpeg
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Is that (second image) a fisheye projection? Yes, it is. The problem, of course, is that it's a cropped fisheye. The lens has a field of view of 115°, far less than the claimed 180° or the actual 155° of a real fisheye lens. And it's hard to claim that the rectilinear image is less distorted than the fisheye image. Here from the right-hand corner:

 
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But re-reading the message, it seems that this person didn't want to stitch just a single image: he specified his fisheye format as 175° diagonal, which you just plain can't get with a single rectilinear image. So there's probably more fun coming.


Saturday, 6 March 2021 Dereel Images for 6 March 2021
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Faking fisheye projection
Topic: photography, technology, opinion Link here

As planned yesterday, took a sequence of shots to create a “fisheye” view, using the Leica Summilux 25 mm f/1.4, simply because that's a “standard” lens. It took 5 rows of 7 shots to cover what I expected to be the complete area, a total of 105 shots (3 each at different exposure for each position).

I was trying to emulate this view, a single shot with the Olympus M.Zuiko Digital ED 8mm f/1.8 Fisheye PRO:

 
https://lemis.nyc3.digitaloceanspaces.com/grog/Photos/20210306/small/house-from-n-single.jpeg
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The first problem was the top row: it was all sky, there was almost nothing to identify the location of the images, and only two were placed. OK, this is just an experiment, and there's really nothing of interest in the sky, so I just cut off the top row.

The result? First rectilinear, then fisheye. Or at least, that's what Hugin claimed:


https://lemis.nyc3.digitaloceanspaces.com/grog/Photos/20210306/small/house-from-n-rectilinear.jpeg
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https://lemis.nyc3.digitaloceanspaces.com/grog/Photos/20210306/small/house-from-n-rectilinear-to-fisheye.jpeg
Image title: house from n rectilinear to fisheye
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I can't see any significant difference, except that the second one is lower resolution: the first is 242 MP, the second only 211. And despite appearances, they have numerous discontinuities in places where I wouldn't have expected them, like round the left-hand window frames. Clearly much more work is needed to make a real panorama with this resolution.

And why is the rectilinear image not rectilinear? Maybe it can't be. Looking at the single photo again, it's not nearly as wide. It has about 155° diagonal, but the stitched images are considerably wider. Rectilinear images max out at 180°, and maybe this image goes beyond that angle.. There is a difference, though, which can be seen in the line of stones at the bottom right.

So: I have images. To do anything useful with them would require even more work.


Stitching large images
Topic: technology, photography, opinion Link here

Hugin is not a ball of fire, though other programs, like DxO PhotoLab, might give that impression that it is. Stitching a normal-sized panorama (up to about 90 MP) takes a couple of minutes. But today I had much larger images to stitch. enblend took 2 hours, 9 minutes and used 26 minutes of CPU time:

grog       95220  96.6  3.2  2201676 1075072 56  R    11:49am      26:00.13 enblend -f240
grog       31417   0.0  0.0    18848    2324 29  S+    1:58pm       0:00.00 grep enblend

So why so long? eureka is an 8 processor machine, so it should produce 26 minutes of CPU time in a little over 3 minutes. But the disks were going crazy, over 100 MB/s. Over the course of the run that's about 750 GB of data transferred.

Configuration? Went RTFMing and found a

       -m CACHESIZE
              set image CACHESIZE in megabytes; default: 1024MB

What does that do? One way to find out. For the second run I set -m 8192. Just before the end I had:

grog       33391  99.7 24.4 16881740 8173360 56  R     2:08pm      15:54.71 enblend -m 8192
grog       38169   0.0  0.0    18848    2316 29  S+    2:34pm       0:00.00 grep enblend

The highlighted 16881740 is the process memory image in kB, so about 16 GB of memory. So CACHESIZE does make a difference, apart from allocating double the setting in memory. Instead of 129 minutes elapsed time it only took 26 minutes and 16 minutes of CPU time (it's too polite to use more than one CPU).

That's worth keeping. How do I set that in my normal build scripts? Looking at them, I find:

      hugin_executor --stitching $i

OK, how do I set image cache size from hugin_executor? As far as I can tell, I don't. There doesn't seem to be any provision for it. Where do I go from here?


Light tents?
Topic: photography, opinion Link here

Lately I've been taking photos of spice pastes before using them. The quality won't win any prizes:

 
https://lemis.nyc3.digitaloceanspaces.com/grog/Photos/20210306/small/Spice-paste-2.jpeg
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How do I get rid of those reflections? Years ago I bought a “light tent”, at front left in this image:

 
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I didn't use it very much. It was oversize and difficult to fold together. I might still have it, but I don't know where, and if I find it it will probably be in the shed and covered in dust.

So how about a new, smaller one? Out looking on eBay and found that they don't make them any more. Instead there are tents with built-in LEDs. How big? Ah, they're too polite to throw that in your face.

The original tents that I saw 12 years ago were 60x60 cm, I decided that bigger was better and bought an 80x80. That's too big, but on closer examination I discover that the modern ones are something like 22 cm on a side. That's tiny! No wonder they don't want to confess. But they're not expensive, and maybe that's just what I'm looking for. The longest side of these paste packages is 20 cm, so they'll (just) fit. To be considered.


This page contains (roughly) yesterday's and today's entries. I have a horror of reverse chronological documents, so all my diary entries are chronological. This page normally contains the last two days, but if I fall behind it may contain more. You can find older entries in the archive. Note that I often update a diary entry a day or two after I write it.     Do you have a comment about something I have written? This is a diary, not a “blog”, and there is deliberately no provision for directly adding comments. It's also not a vehicle for third-party content. But I welcome feedback and try to reply to all messages I receive. See the diary overview for more details. If you do send me a message relating to something I have written, please indicate whether you'd prefer me not to mention your name. Otherwise I'll assume that it's OK to do so.


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