The Exploits of Plouj

This is documentation of how I used Yukon and Seom to video capture a Google Earth trip for a recent video project in Fedora 10. I used the official installation guide as a starting point.

Compile the Seom library

I choose to install both Seom and Yukon in a custom prefix /home/plouj/yukon, rather than the system wide /usr or /usr/local.

$ svn co https://devel.neopsis.com/svn/seom/branches/packetized-stream seom
$ cd seom
$ ./configure --prefix=/home/plouj/yukon --arch="x86" --cflags="-W -Wall" && \
make CC="gcc -m32" && make install LIBDIR="lib"

Note that “–arch=”x86″ and “-m32″ are only necessary for me because my operating system is 64bit and I need 32bit versions of seom and yukon (to work with 32bit Google Earth).

Compile and install Yukon

$ svn co https://devel.neopsis.com/svn/yukon/branches/rewrite yukon
$ cd yukon
$ ./configure --prefix=/home/plouj/yukon/ --libdir="lib" --arch="x86" && \
make CC="gcc -L/home/plouj/yukon/lib -I/home/plouj/yukon/include -m32" && \
make install

Install Google Earth for Linux

Obviously get it here: http://earth.google.com/

Modify the Google Earth startup script

Since I chose /home/plouj/bin/ as the “Binary path” for Google Earth I was editing /home/plouj/bin/googleearth. All I had to do was to add yukon/seom library and executable paths at the end of the script:

...
cd "${GOOGLEEARTH_DATA_PATH}/"
LD_LIBRARY_PATH=/home/plouj/yukon/lib/:$LD_LIBRARY_PATH \
PATH=/home/plouj/yukon/bin:$PATH exec yukon "./googleearth-bin" "$@"

instead of the original:

cd "${GOOGLEEARTH_DATA_PATH}/"
exec "./googleearth-bin" "$@"

Capture

Finally, the capture process is well documented on the Yukon website.

Blender sequencer gives the ability to optimize rendering of repeated frames by keeping the first result in memory cache and re-using it. Depending on the project, it might be necessary to increase this limit beyond the default 32MB. If the limit is surpassed while rendering a single frame, Blender clears the cache before proceeding to the next frame and the re-renders everything from scratch.

Increasing the cache limit is easy to do in the UI:

This setting is stored in the user’s preference file (~/.B.blend on Linux systems) and, therefore, applies to all projects. However, rendering from the command line requires using the -b argument, which explicitly ignores the user’s preference file. Apart from editing and re-compiling the Blender source code, I found only one way to increase the memory cache limit.

The trick is to use a Python script, like below, to change the user preferences before rendering the scene:

import sys
import bpy

def main():
	bpy.config.sequenceMemCacheLimit=4096

if __name__ == '__main__':
	main()

Add the script to the command line like this:

./bin/blender -b sample-static-text.blend -P render_settings.py -a

Note that the order of arguments matters because first we need to load the scene (with -b), then change settings through Pythons (using the -P option) and finally render the animation (with -a). Also, you need at least version 2.49a of Blender for this to work.

For reference, here’s is the the source file which hardcodes the 32MB limit:

intern/memutil/intern/MEM_CacheLimiterC-Api.cpp:

...
static intptr_t & get_max()
{
        static intptr_t m = 32*1024*1024;
        return m;
}
...

Here is how to configure a Fedora workstation to use OpenDNS nameservers in a network with corporate DNS and DHCP servers without loosing access to their services.
This was done on a Fedora 9 machine with dnsmasq being the local DNS server. It should also work on newer Fedora versions and even other GNU/Linux distributions.

The setup is actually very simple and unobtrusive. It is only necessary to properly configure a local DNS server and then force 127.0.0.1 to be used as the only nameserver instead of the corporate DNS servers.

First you need to configure dnsmasq as follows:

/etc/dnsmasq.conf

# don't use the /etc/resolv.conf file anymore
no-resolv

# OpenDNS nameservers:
server=208.67.222.222
server=208.67.220.220

# Force corporate nameservers for corporate.domain.com lookups
# OpenDNS wouldn't be able to answer such queries correctly
# adjust to suit your network
server=/corporate.domain.com/10.1.1.1
server=/corporate.domain.com/10.1.1.2

# only respond to queries from the local machine
listen-address=127.0.0.1
bind-interfaces

conf-dir=/etc/dnsmasq.d

Then you need to go into NetworkManager and set 127.0.0.1 as the DNS server to be used:

This will result in the following important settings added to your network scripts:

DNS1=127.0.0.1
PEERDNS=no

I’ve noticed two minor problems with this setup:

1. the corporate DNS server names are hardcoded in the configuration. Usually they are determined automatically by the DHCP client.
2. restarting the dnsmasq service sometimes shows this error:

   dnsdomainname: Host name lookup failure