Notes on photo sphere/panoramic EXIF metadata

• Google's EXIF/XMP metadata tag specification for panoramic images
• Panorama images with sky are to have a negative value for the CroppedAreaTopPixels tag. (The panoramic viewer of Facebook ignores the value altogether, though, and assumes the horizon in the middle of the picture.)
• If a camera or software normally produces panoramic images with cylindrical projection, then doing a vertical capture actually produces a transverse cylindrical image. There is no standardized value for the EXIF ProjectionType field to cover this. (One option is to reproject them to equirectangular — which, again, is not very well supported.)
• Facebook's document on what tags to set
• The Facebook web interface insists that FullPanoHeightPixels be half the size of FullPanoWidthPixels. Else you get “no new photos were uploaded”.

/ Tags: Photo.

Simple bandwith monitoring with iptables/xt_quota2

Add some iptables rules without a target:

iptables -t mangle -I PREROUTING -i ppp0 -m quota2 --grow --name incoming
iptables -t mangle -I POSTROUTING -o ppp0 -m quota2 --grow --name outgoing

The quota2 match counts traffic as packets pass this rule, and makes the value available through procfs. This makes it superior to everything that tries to grep and interpret the output of `iptables -L`.

This can easily be wired up with rrdtool to produce some graphs. The following snippet contains the script that should be run every 60 seconds from cron.

#!/bin/bash

q="/proc/net/xt_quota";
file="$HOME/internet.rrd";
if [[ ! -f "$file" ]]; then
    rrdtool create "$file" --step 60 \
        DS:incoming:COUNTER:120:0:U \
        DS:outgoing:CONUTER:120:0:U \
        RRA:AVERAGE:0.5:2:$[60*24*180] \
        RRA:MAX:0.5:2:$[60*24*180] \
        RRA:LAST:0.5:2:$[60*24*180]
fi;

now=$(date +%s);
in=$(cat "$q/incoming");
out=$(cat "$q/outgoing");
rrdtool update "$file" "$now:$in:$out";


The final graph picture can then be produced:

file="$HOME/internet.rrd";
type="AVERAGE";
rrdtool graph "$HOME/internet.png" --start -86400 \
    -a PNG -t "Interface ppp0" -v "Bytes/s" \
    -w 800 -h 400 -M \
    "DEF:x_incoming=$file:incoming:$type" \
    "DEF:x_outgoing=$file:outgoing:$type" \
    "CDEF:y_outgoing=x_outgoing,-1,*" \
    "AREA:x_incoming#008800:Received" \
    "AREA:y_outgoing#880000:Transmitted"


Posted 2009-02-24 01:02 / Tags: Iptables, Linux, Monitoring. / link