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11 Aug

I recently migrated all the content from this blog to my new website!, I’m looking forward to see you there.

Hi all,

I hope you are having a great summer! Just a quick note to say that I’m migrating my blog to my new website. I hope you like it and continue following my research. Don’t hesitate to contact me anytime 🙂

Online tool to convert .kml to .shp

1 Aug

Hi guys, today I just wanted to share with you a very useful tool that I found.

Is called Kml2Shp and it exports online any kml to ESRI shapefile format or the other way around. Very nice tool 🙂

The importance of the correct use of projections in GIS data

21 Mar

Hello guys,

Today I was explaining somebody about the consequences of messing up the geographic coordinate systems and projection when you are working with GIS data.

In reality once you decided which projection you are going to work with, to have all your data with the same projection or to transform data that is in another projection is very simple. However, the problem comes when you mix data with different projections such as, for instance, a DEM with one CS and a shapefile with another. Although software like Arcgis warns you when you are working with data in two different systems, it doesn’t stop you from doing spatial analysis or any other kind of work. To illustrate this problem (that can be quite serious if you get it wrong), I’m going to show you the difference using two point shapefiles with THE SAME DATA but DIFFERENT PROJECTION.

The red dots represent archaeological sites that were recorded in ED_1950_UTM_Zone_30N and the black dots are the same sites but projected as WGS_1984_UTM_Zone_30N

Different projections

Although the difference may not seem large (182.923 m), in fact, when performing spatial analysis this will have its impact in the results. I know that in archaeological cases this might not be an error that cause a major disaster like calculating wrong, for instance, flooding levels of a damn. However, it is highly important that you get it right in order to have correct results.

There is a very useful resource where you can find the main geographic_transformations_complete, parameters and areas of use released by ESRI that can be used with all “project” tools in Arcgis.

Ok, I hope this is useful and see you soon 🙂

FREE Aerial photography and remote sensing data

1 Mar

Hey guys,

I hope you had a good weekend. These past days I have been a little bit quiet but is for a good reason. I have been doing a very entertaining research on sources for aerial photography. So, for my friends that do research in the amazing Andalucia, you are probably aware of this site which is from the Spanish government and that allows you to download all the orthorectified aerial series, from the 1956 flight and the 2007 infrared to the colour 2009, some of them at 0.5m resolution!  To tell you the true I’m very impressed with the efficiency of the guys from the Junta de Andalucia as they not only have all the material free and available, but they  also have loads of environmental information online and free as well. All cartography units should follow their schema…

Anyway, I also found this NASA site where you can download some of the Landsat series also for free. Just be aware that it doesn’t work with Chrome :p

Well, see you soon!

GIS and Google Earth

24 Feb

Hello again guys!

Today somebody asked me about getting GIS data into google earth.

This software has the great advantage that you can see loads of different data that you don’t necessary have in your regular GIS, such as pictures of a site that is of your interest uploaded by the community , tracks, wikiinfo and so on. So there are good reasons for you to want your gis regular data displayed here. The problem that my friend had was that when he “imported” his data into google he realized that it was a little bit “off” place.

Ok. This is basically due because the coordinate system he used was the one he had originally set for his data. KML only supports WGS84, so in order for you to display your data correctly you need to “reproject” your data to to WGS84. In arcgis (as in other software) this is really easy.

Happy modelling 🙂

Free GIS and Spatial Data Analysis Software

23 Feb

Hey guys,

Just a quick post to tell you about this great software I found recently.

MapWindow seems to have great potential to get layers into a diversity of formats, while GeoDa offers all these facilities:

  • Data Input and Output
    • read and write shape files
    • copy graphs and maps to clipboard
    • save maps and graphs to bitmap file
  • Spatial Data Manipulation
    • create point shape files from text files
    • centroids for polygons
    • Thiessen polygons from points
    • contiguity based spatial weigths for polygons
    • distance based spatial weights for points and polygons
  • Visualization and Queries
    • graphs, maps and table
    • linking and brushing of all maps and graphs, multiway linking of table
    • spatial selection on maps
    • query selection in table
  • Mapping
    • quantile and standard deviational maps
    • outlier maps: box map and percentile map
    • rate mapping and smoothing: excess risk map, Empirical Bayes smoothing, spatial smoothing
    • map movie
  • EDA
    • histogram
    • box plot
    • scatter plot
    • full dynamic linking and brushing
  • Spatial Statistics
    • Moran’s I
    • Moran scatterplot: univariate, bivariate, EB corrected
    • LISA local Moran: univariate, bivariate, EB corrected

    I hope is of some use to you! 🙂

    Recursos de SIG y Geomatica para Latinoamerica (GIS & Geomatics for Latin America)

    21 Feb

    Esta vez les escribo para compartirles un excelente sitio de recursos de Geomatica y SIG Libre que puede ser especialmente util para quienes trabajan en Mexico y otras partes de America. Espero que hayan tenido un buen fin de semana y pronto les platicare sobre cuestiones tecnicas respecto a la combinacion de analisis de visibilidad y movimiento 😀

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