9.13.2011

Have you tried Google Fusion Tables?

Apart from the awesome Google Maps and Google Earth. Did you know that you could embed your spatial data in Google Fusion Tables?

Google Fusion Tables is meant for visualizing your data in a spreadsheet. It produces cool charts (bar, pie, scatter, line) for just about any formatted table you have.


You may input a spreadsheet directly from your Google Docs or you may also opt to create a new table from scratch. the steps are easy, just follow the step-by-step instruction at http://www.google.com/fusiontables/ .

Here's a cool line chart that I have created before. It shows the series of oil price hikes since we bought a car last year. It gives me an idea where our next gas refilling station will be. Pretty neat display too. And kudos for it being interactive. Yay!



Now for the geospatial people/geek, you might want to try using this Google Fusion Tables for visualizing your latest database. As long as you have some data with spatial components i.e. geographic coordinates (latitude, longitude), this is already good to go.

What's nice is that it is really interoperable with other Google Products e.g. Google Docs, Google Earth, Blogger, etc. It even has the option to export the created file in KML format.

I played around with our data last night and it was a pleasant surprise. Here's my first try to plot in Fusion Tables.

In the map below is a result of our tree survey, using an Android App,  along the Engineering grounds of UP Diliman.  This initial database is in preparation for a collaborative mapping of trees in UP Diliman for carbon footprints mapping purposes. Try clicking with some points and you'll get to see the attributes of that certain tree e.g. diameter, height, species etc. I'll have to explore more of this, I hope you will too...



Now for those who are not in the geospatial field, this Google Fusion Tables would still surely be of big help. You might want to visualize some trends or analytic report or some playing with a URL or perhaps some favorite tourist destinations with attributes that you want displayed in a map.  Time to experiment folks. Let's play Google(^_^).

Applying inSAR principles to detect surface deformation in Metro Manila

I have just attended an InSAR training  showing how to detect surface deformation through phase differences between SAR signals.

SAR satellite transmits microwave to earth and receives reflected microwave signals from earth surface. The intensity of received microwave indicates electromagnetic characteristics of objects, and phase indicates distance between aperture and object. Surface deformation is measured by the difference in two observed phases. The observed phase differences still contains errors that ought to be corrected along processing enumerated by the steps below.

  1. Getting SLC (Single-Look Complex)
  2. Co-registration (registration of Master and Slave images)
  3. Interferometry ( measuring phase differences)
  4. Corrections (Removal of Orbital and Topographic Fringe)
  5. Phase Unwrapping (integration of extracted to actual phase difference)
  6. Geocoding
  7. Visualization of Results in ENVI
  8. Analysis and Interpretation
With the use of ALOS Palsar images from two different instances in time, the InSAR processing flow is initiated in a LINUX environment with the use of SIGMA-SAR software. 

After a real image and an interferometric image is produced, these image files are then viewed, further processed and analysed in ENVI. 

Our study area is Metro Manila, Philippines. Two ALOS Palsar images were used (2011 and 2007 images).

The following images were produced. By linking displays, the suspected are of deformation is along the area enclosed by the ellipse.



This is a close-up view of the interferometric image and the deformation (subsidence) is approximately 9.2cm along Caloocan City, Metro Manila.

The issue on land subsidence within this area is beyond the scope of this post. Land subsidence , as suspected to be in Caloocan City, may be due to its soil type and its proximity to Manila Bay. The results should also be compared with a current surface deformation study such as the results of a differential GPS campaign.

I have just finished the RADAR training by JAXA-Sentinel Asia

 Being part of the GPS Team in our office, we are tasked to map the crustal deformation along the Philippine Fault as well as other tectonically active locations in the Philippines using Differential GPS.

Apart from GPS , there are other means of quantifying such deformation, one is through remote sensing with the use of satellite images. RADAR is a means to remotely sense and analyse an environment such as the Earth.

I have just been part of a RADAR training, specifically inSAR (Interferometric Synthetic Aperture Radar) that was held in the Philippine Institute of Volcanology and Seismology (PHIVOLCS) Auditorium held last September 5-6. This technical training was brought to us by JAXA - Sentinel Asia.



It was an engaging experience and I surely learned a lot. Will have a separate post for that later. I am looking forward to applying the principles in the current research projects that I am in.