4.26.2011

How to go back from Yahoomail BETA to All New Yahoomail

I have tried the new Yahoomail BETA. I am currently using the All new yahoomail which is an improvement of the Yahoomail Classic. I like the features so I adopted it and am using it for more than two or three years now (really am not so sure when I started adopting it).

This morning I received an e-mail from Yahoo saying that they are improving the mail service. I then tried the BETA version. I say I don't like it that much because of the following reasons:
1. I'm not interested with the updates tab.
2. It has more advertisement than the previous version.
3. I don't like the integration of the Yahoo (with top stories, popular searches, etc.) page inside my mail.
4. I can't customize my chat status.It became simply Available, Busy and Invisible to Everyone.
5. I don't like windowed chat like that of Gmail. I prefer the tabbed chat from the All-new-Yahoomail.
6. My conversations are archived.
7. I don't like Facebook integration.

Anyways, simply put, I'm returning to my old All-New-Yahoomail. Here's how:

Help>Leave the Mail Preview and told them I'm not ready to switch plus my enumerated comments above.> Pressed continue. And I'm back.

4.05.2011

Free Open Street Map data (i.e.shapefiles etc.) for the Philippines

Free Road data extracted from Open Street Map made available by Cloudmade.

Datasets for different countries are also available.

GEOFABRIK also made OSM data freely-available for us. It is not partitioned by provinces like that of Cloudmade though. 

The datasets are very useful. GREAT!

I go really excited whenever I get to discover free datasets being catered to everyone. When we get to share our contents, that's when better things come our way - our data being improved, information disseminates and public awareness increases. 

I hope our local government is making some effort to utilize this free and useful information for planning and multi-criteria decision making. I hope. (^_^)

4.03.2011

How to prepare elevation range of SRTM in ArcMap for 3d visualization in ArcScene

If you have a DEM, you might want to view it in 3D. For me, I do geovisualization in ArcScene, VTP or for simple presentations I use Google Earth.

DEM or digital elevation models contain the heights of our terrain. It has a commonly interchanged counterpart term known as DTM (digital terrain model). DEM differs from DTM in the sense that DEM is not the elevation from the ground per se. It is the height with the buildings and other cultural features. DTM on the other hand gives the height of the bare ground.

For DEM, we can obtain freely available datasets such as SRTM and ASTER. SRTM resolution is 90m X 90m for the Philippines while ASTER is 30m x 30m. Though ASTER is of higher ground sampling distance than SRTM, researches show that SRTM still proves to be more accurate than ASTER. 

So for the purpose of visualizing our terrain in 3d. What we would first want to do is to prepare the DEM (i.e. SRTM DEM ) for processing. If we fail to do this, we will be confronted with a very large range of elevation values that ArcScene or our visualization software can't reconcile and we end up not seeing anything on our screen.

So here are the steps for doing it in ArcMap.
Example: if we have the DEM named ISABELA, run these codes in the Spatial Analyst> Raster Calculator.

temp = con ( [ISABELA] >= 32768 , [ISABELA] - 65536 , [ISABELA])

temp1 = setnull ( [temp] < -9998 , [temp] )

to remove the NoData, run the following commands
temp2 = Con( isnull( [temp] ), focalmean( [temp1] , rectangle, 5, 5 ), [temp1] )
 temp3 = Con( isnull( [temp2] ), 1, 0 )
The resulting grid is in floating point format so convert it back to integer using,
Final = Int( [temp3] ) 
Make the Final GRID DEM permanent by right clicking Final layer> Make permanent then choose location and file name.

You may also opt to export it in other formats such as geoTIFF for use with other visualization softwares. You can easily do this by right clicking the DEM GRID> Export Data then choose type of raster, path and 13-character filename.