Most digital cameras bundle some kind of software to create panoramas; a
collection of pictures stitched together to form a single, seamless picture.
I was quite disappointed with Canon’s “stitching” software (came bundled
with my S50). The software simply pastes the pictures together, creating a
very heavy and noticeable blur at the edges, in a lame attempt to hide the
seams. Dissatisfied with this solution, I googled around a bit until I found
Hugin, an excellent GUI for the Panorama
Hugin can stitch your pictures perfectly, even if you didn’t use a tripod or
if took them at different camera tilt angles (a common situation if you’re
holding the camera with your hands). Unlike most software in its category, it
uses “control points” to “glue” the images together and compensate for the
differences in tilt.
Hugin does not try to hide the seams that connect your pictures. To make a
perfect panorama, you’ll also need Enblend,
which takes care of making the seams in your panorama invisible.
The results are indeed impressive, and the seams are very hard to locate. I
recently took some pictures of mountain bike trails in Ocala, Florida, and joined them
using Hugin+enblend to create this panorama.
For further reading, try this page,
which explains in detail how to use Hugin and Enblend to make create a panorama
from a set of images.
Keywords: camera, panorama, hugin, pano-tools, enblend, autopano, picture, canon, stitch
Retrieving the current time under Unix is easy. Just use the
Fri Apr 1 16:27:14 EST 2005
You can also use date formats to output the date in a specific way (so it can
be used in scripts, or to form filenames):
$ date '+%Y%m%d-%H%M%S'
But what happens if you want to see the GMT time, not the localtime? Just manipulate
the TZ variable to fool date into believing we’re sitting on the GMT line:
$ TZ=GMT0 date
Fri Apr 1 21:30:21 GMT 2005
Another very frequent problem in scripts (specially log rotation scripts) is how
to get yesterday’s date. Again, we can solve the problem by cleverly manipulating
the TZ variable:
$ TZ=GMT24 date '+%Y%m%d'
Keywords: date, time, linux, yesterday, GMT, timezone, TZ
What good is a system clock if you can’t keep it synchronized to the rest of the world? Well, hopefully, this is an easy task using the NTP daemon.
You’ll first need to install the NTP or XNTP packages, depending on your Linux/Unix version. Then, just create a file named
/etc/ntp.conf with the following contents:
This assumes you are connected to the internet.
Restart your NTP package and monitor the synchronization progress with the
$ ntpq -p
remote refid st t when poll reach delay offset jitter
*time.nist.gov .ACTS. 1 u 485 512 377 69.062 -43.727 1.954
+ntp-1.gw.uiuc.e truechimer.cso. 2 u 513 512 377 63.117 -49.113 1.767
+hickory.cc.colu navobs1.wustl.e 2 u 40 512 377 44.482 -47.185 2.675
-cs.columbia.edu clepsydra.dec.c 2 u 33 512 377 44.732 -51.191 3.245
Pay special attention to the “tally code”, the caracter to the left of the hostnames.
You’ll want to see “*” and “+” there. No signs or minus signs only mean your system
is not properly synchronized. Also, your system may not be too far from the “reference” clock.
If that’s the case, ntpd will panic and exit. To prevent this, set your clock manually
to something close to the reference time or use “ntpdate” to do it for you automatically.
Keywords: time sync, ntp, ntpd, linux, unix, example