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Saturday, 6 March 2021 | Dereel | Images for 6 March 2021 |
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Faking fisheye projection
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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:
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:
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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
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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?
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Topic: photography, opinion | Link here |
Lately I've been taking photos of spice pastes before using them. The quality won't win any prizes:
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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.
Sunday, 7 March 2021 | Dereel → Ballarat → Dereel | Images for 7 March 2021 |
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Phone crash?
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Topic: technology, opinion | Link here |
Came into the office and picked up my phone this morning. Pressed the power button briefly. Nothing. The thing had shut down.
Why? It was on the charger. Not plugged in properly? No, after rebooting, it showed 100% charge. I haven't seen that on a phone before. Was it a crash? A deliberate shutdown? People suggest that I go looking for log files, but can I bear the thought?
Ballarat market again
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Topic: general, gardening, opinion | Link here |
Off to the Ballarat Market today for the first time in over a year, and thus since the beginning of the COVID-19 pandemic. There are signs:
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I asked the people at the entrance about the first sign, and they said that to forget it: they had forgotten to remove it. But this photo was taken after we left again.
The market was also pretty empty. Normally this hall is full on both sides:
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And not surprisingly we didn't find much: some sweets and snacks, and that was all. I had hoped to find some spring bulbs for the garden, but possibly we were too early. But the whole thing wasn't really worth the effort (and the somewhat delayed breakfast). We should investigate buying this sort of thing on line.
More wine
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Topic: food and drink, opinion | Link here |
On the way back from Ballarat, stopped in to the post office in Napoleons, which is open even on Sundays, to pick up some wine that I had ordered—8 cases.
Oh horror! Once again I had the wrong variety! 3 cases of Cabernet sauvignon instead of Shiraz!
My fault or theirs? Until proof, left the three cartons there and back home where I found, of course, that it was my fault. Why? After the last time I looked very carefully. It could be the somewhat hard-to-navigate web site, but that's not much of an excuse. I really must read the checkout invoice more carefully.
And what do I do about it? I recall that they're prepared to refund, so that's an option. But the surprising thing about the Chardonnay that I got in October was that I actually preferred it to the Sauvignon blanc that I normally drink. So I should at least give the Cabernet sauvignon a chance.
More frying pan insights
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Topic: food and drink, opinion | Link here |
Today I got round to trying out the new frying pan (and explicitly not frypan) with lid that I discussed on Wednesday.
Is that interesting? Well, surprisingly, yes. It heated unevenly. Here the large slice of bacon had been turned over; the right-hand side had been on the edge of the pan, and the left-hand side towards the middle.
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Clearly the left-hand side had been cooked considerably more than the right-hand side. Similar considerations apply to the smaller piece in the middle of the pan and the one on the edge.
Why? Time to look at the underside of the pan:
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That dotted area is the area heated by induction. It's only 18 cm across! The pan has a diameter of 28 cm, though that's to the top; the cooking surface is about 24 cm across:
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But that still means that the heating surface is only about 56% of the cooking surface. No wonder it heats unevenly.
How is it with other pans? Here another pan of the same size (and from the same maker):
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Here the heating surface is of another kind, but it's 22.3 cm across, 93% of the cooking area, and probably enough to ensure even heating—if I understand the composition of the bottom correctly.
So: Yet Another return? Why are frying pans so complicated?
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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