Two weddings and Tiger Footprints

It is that time of the year when I visit my family in India and throw in a drive by tour of another place in Asia. This trip is almost round the world in its scope - Adelaide, Singapore, HongKong, Kunming, Kolkata, Dubai .... back. There are always memorable things at each spot. Singapore airport is just too familiar, but on 2 flights I sat next to Capgemini employees flying in and out of China (from Australia and to India). Something huge is brewing.


The highlight of HongKong was the busy life-style, crazy shopping and the hybrid cultural wedding. The lights make for great photography and testing out of my new 4/3 camera. Some serious lens shopping coming up. The wedding was a fun, great venue, good scale and +Rowan Fry looked understandly over the moon. The best part was the entrance in traditional chinese gear, he would have made a rather respectable official in imperial china. I wish them a happy life together.

Last week I attended another wedding in Bengal. The contrast was stark, the rush, the colours, the food. The only thing that was constant was the hot wire cut foam decorations, the flowers and the suit I wore to the other wedding. The wedding invitations extend to whoever bothers to come, I hardly knew anybody, not even bride and the groom. Felt a bit like a wedding crasher, till we went to see the bride's dad, he was laid up with all the stress from getting the feast organised for some 600 people.

The last few days we toured the Sunderbans with a Backpackers group aimed at foreigners, much more relaxed than trying to do it packed like sardines in local style. There seems to be zero-respect locally for the Sunderbans, since the majority have not been lucky enough to see the tigers, all believe no tigers exist. They should perform 3D photogrammetry on tiger footprints, lay out some tiger sized dolls and change the holiday season to coincide with tiger mating season. Only then will people believe tigers do exist. Saw plenty of crocs though and some crazy tourists to keep us company. I was both local and foreign, had fun teaching Bengali - managed to teach a Canadian to count to ten. Should start some word association based Bengali learning kit.

On map Augmented Reality with Vuforia + Unity

I have been doing some more development with Android, using a different (and easier) renderer this time than the still nascent OpenSceneGraph port, with a bit of Augmented Reality thrown in via Vuforia.Which basically functions as an OpenCV port with image orientation recognition thrown in optimized for Qualcomm's Snapdragon SoC. The feature detection and texture packing is annoyingly performed at the Qualcomm site, I guess they want to keep track of images over which features are detected and prevent inappropriate use by script kiddies. From the looks of FastCV, the features are either MSER or Harris corners.

I already have Android dev kits going so the fun bit was in importing our nice models into Unity and sending the package over to the device. Textured models seem to import best into Unity via Blender, after a bit of copying around of textures and forcing association with the right materials.

Setting up the scene in Unity is fairly straight forward, the Vuforia SDK delegated to Unity for rendering and simply attaches a handler to the Camera. The visible object is automatically centred in the scene so the camera to target geometry is irrelevant in this case. However lighting is not, so a bit of tweaking in lights is necessary for a nice model render. Switch all the materials to diffuse/mobile to load the appropriate shaders in GLES2. Add an LODGroup node if the model is getting too big, though I was able to render some 100,000 triangle models.

When all is set the tracking can begin. I lined up the model to our orthoimagery, the screenshot does not do it justice. It is really cool watching a 3D object stick out of your screen. Everybody at work is very used to viewing things in stereo, but multi-perspective 3D still has a wow-factor.

Building OpenSceneGraph with Android NDK

I have been rapidly picking up Android development for the last 2 days with Native coding in C++ thrown in. Cross compiling for embedded systems is nothing new for me having played with Beagleboards in various incarnations, the Hawkboard and Pandaboard. Neither is JNI, I did a fair bit of JNI work while at CSIRO trying to make NetCDF faster.

So to build OpenSceneGraph for Android (I am using my Nexus S running 4.2), do the obvious:

• Get OSG source
• Get ADK
• Get NDK
• Get ADT if you are Eclipse fan like me
• Get Sequoyah, CDT and whatever else Eclipse wants to build native code.

Build OSG for Android with whatever hack you can imagine. I ended up getting CMake to generate with NMake build files, but built directly using ndk_build afterwards since the MSYS shell could not access DOS commands ndk-build seems to call. Install automation did not work either so I copied OSG headers over by hand into the build directory. It took a while to build, the NDK compilers are rather slow, in the future I will run with -j 12 to take advantage of all my cores.

The next bit was rather easy since the OSG Android sample is already configured for Eclipse. I had to fix up settings with MSYS for bash. Most tutorials refer to cygwin for Linuxy utilities, but I loathe cygwin and I already a have a bunch of MSYS installs floating around through OSGeo4W and Git-bash. The include files and compiler checks are rather strict in Eclipse and any errors in the IDE will prevent uploading the build, be naughty and just delete the errors due to ADT bugs. This is just a proof of concept after all. I had to change a few little things like false to JNI_FALSE to keep the compiler happy. After some toing and froing with gnustl_static, the whole thing built and ran fine.

I wanted to have jpeg textures embedded in the .ive and .osgb files displayed as well as load models with PagedLOD's over http. So I needed to link the little trivial application to curl and jpeg in their Android native incarnations. The hard work has been done already and you can get thirdparty bundles. The first attempt with 8192x8192 textures expectly blew up on the little platform, but atleast libjpeg seemed to be working, I squished textures down to something sane. Libcurl works to download a file hosted on our webserver just fine, but you can't wait for an eternity on this plaform, unless the basefile is a few kb and links to the rest via LOD's the GL context will be lost before the download finishes. Overall it was a fun experiment and I am glad i managed to load a Jesus statue to celebrate this festive season - though it represents death rather than birth.

Blender as a Python module, happy coding from Eclipse

This post is going to be a reminder to self in-case I ever need to do this again, or I am cloned and the clone is wondering how the original spent his time.

Get Blender source
Set options as pointed by IdeasMan to build as Python module
Compile with Visual Studio
Set BLENDER_SYSTEM_SCRIPTS as an environment variable, small undocumented caveat where reading the source actually helps.

Import Bpy and Python 3.2 in Eclipse and use Blender algorithms in headless mode.

Trivial CMAKE for OpenSceneGraph

It is often fun to get open source projects working with Visual Studio since a lot of build systems leave out a few Microsoft specific vagaries. With CMAKE life in the last few years has become much easier, though sometimes it requires a bit of digging to locate the right incantations to pull in the right dependencies for a trivial project.

CMAKE_MINIMUM_REQUIRED(VERSION 2.6)
PROJECT(AeroViewer)

SET(TARGET_SRC aeroviewer.cpp )

find_package(OpenSceneGraph REQUIRED osgDB osgUtil osgGA osgViewer osgText)

ADD_EXECUTABLE(aeroviewer ${TARGET_SRC})

INCLUDE_DIRECTORIES(${OPENSCENEGRAPH_INCLUDE_DIRS})
TARGET_LINK_LIBRARIES(aeroviewer ${OPENSCENEGRAPH_LIBRARIES})  

The aim of this quick dash is to add a screen overlay with the company logo to the default osgViewer. This requires adding a geometry node to the scene with some static geometry in camera space. Which ends up being equivalent to a HUD in osg parlance. After a bit of tweaking and rotations in texture space I got this, not too bad for a cold-start in OSG land. This bit of sample code is better for HUD's than the tutorial, the required projection and modelview matrices are encapsulated by the CameraNode.

Why is gold valuable anyway ? - Midas and Supernovas

Growing up as a child in India in a family of goldsmiths it is hard to ignore the role gold plays in perception of wealth and daily conversation. My uncle would often refer to "stuff" or "maal", meaning gold. On my last visit the regular obsession was checking the current gold price from the wholesalers via SMS. According to a recent article - Man's addiction to gold - India holds pretty large stockpiles of the metal in the proverbial family jewels. It changes hand at marriages as gifts and dowry.

Gold has no intrinsic bio-chemical value which supports life as the cautionary tale of King Midas points our. Its inherent inertness however gives it great value in the burgeoning electronics industry and it is very rare to start with anyway due to the cosmic element forming processes making it harder and harder to produce heavier elements. The vagaries of nucleosynthesis are so universal that they have even made it to being a Hollywood plot device in "Cowboys and Aliens" where aliens set up a gold mine.

The ultimate statement on how we value things comes down to supply and demand - gold is in short supply due to its nuclear weight and on high demand due to its permanence once acquired. We now just need to find suitable biochemistries or bioelectronics to make it part of a living body. Gold abundance is a measure of the midas touch of supernovas.

Making Furniture from Banana

I had a solid grounding in natural fibers and polymer chemistry thanks to my father. My mum still has a picture of him happily holding a sisal leaf. We took this picture in the plantations just outside Mombasa. Well the agave family is pretty notorious, apart from sisal it also gives us pineapples and tequila.

So I tend to talk about the wonders of polymer chemistry often. I kept rambling at the Augustiner Biergarten in Munich about natural fibers, hair and aramids, to slightly disbelieving stares. Ended up learning a bit about making violins out of Kevlar.

The whole chain of thought started on the plane from Adelaide to Kualalumpur. I sat next to Ed organising the overseas operations in Egypt for Papyrus inc and making veneer out of banana stems. He treated me to a nice time in KL on condition that I show the same consideration to any travelling PhD student I meet in the future, when I am a director or something. Otherwise it was a great conference featuring a visit to the EADS solar panel and rocket engine manufacturing facility - which used to serve as the tank manufacturing facility at its inception. As well as plenty of nice technical sessions and a strange conversation regarding compressed sensing and the difference between SAR and optical.

I finally did the IGARSS Conference review survey today, so getting the blog out is timely. May be I will present about point clouds at the next conference and take a break from the SAR stuff. Check this video for what I have been doing recently.