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.
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:
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:
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.
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).
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:
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.
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:
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.
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?
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
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