Posts

Using Dropbox to Host your webmap

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Dropbox, surprisingly could be used to host a static web page. There are other providers too like Google Drive. But its capabilities will be discontinued after August 2016. And by the this functionality, we can host a simple webmap (or little bit complex, I dont know, didnt test it yet) using this service. The hosting procedure is quite easy, 1. Make a dropbox account and login 2. Looks for "Public" folder and make a directory there. 3. Write your own webmap, for example I copy an html file somewhere, and edit it to include my Mapbox webmap into its DIV Tag, then I just place the html to the directory created on step 2. The code looks like this : 4. Save it to Html and place to the directory on the step 2. 5.  Then left clik on it, > Looks for "Copy Public Link" 6. Paste into browser. 7. Click this LINK to see how the code in step 3 looks like

Surface Reflectance in ArcGIS

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I just noticed that at the recent version, ArcGIS has been implemented some sort of physical liked surface reflectance generation function in its image analysis module. The function is called apparent surface reflectance. An algorithm which takes into consideration all the iradiance related information stored in the metadata (sun azimuth angle, sun elevation angle, radiance gain/bias etc) to derive surface reflectance dataset, although it is not pure physical (because it does not consider the atmospheric condition at the acquisition date). The algorithm target the illumination condition which is theoretically should be similar between dates and wavelengths (differs in reality due to atmospheric effects, sun angle/position and sun-earth distance in every season etc) so it could be usable for color balancing and mosaicking (not sure if it will add certain degrees of accuracy in image classification). I make a guide if you want to try it by yourself

Download Landsat 8 Data Using SnapSat.Org

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A new landsat-8 data provider has been added Using simple interface you can straightforwardly download landsat-8 data either just some bands or full dataset. This portal utilizing Amazon S3 free access Landsat-8 repository, so it will have some data acquisition delay compared with official USGS repository (EarthExplorer, GLOVIS, REVERB). Based on the test I conducted, I think data access thru this portal is greatly useful if you just need some quicklook or visual interpretation needs. Oh btw, Landsat-8 data obtained from this portal is reprojected to Web Mercator Projection, so if you need the data in UTM or Geographic Projection, just reproject it using ArcGIS, QGIS or other Geospatial softwares.

Creating Simple Web Map Using QGIS

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From day to day, QGIS is getting bigger and bigger. Continuous and expanded support from open source geospatial developer has made this software go beyond its initial development. More and more tools/plugins has been created and offering more flexibility and features to the software. It is fair to said that this software is now became an ideal example of successful non commercials geospatial movement. Personally I am starting to count more on this software because it is now offering some distinct tools unavailable on commercial counterparts. The keys of QGIS for me are simplicity, straightforward how to, and free to use. I am not kidding, below is an example how the simplicity means. A Tutorial about how Online Map could be deployed easily from QGIS. Using fast growing to use WebMap Frameworks like Openlayers or leaflet, a not experienced and programming literate user could make an online webmap with sophisticated looks just with some clicks. Check it out below. And last b...

Trying out NNDiffuse Pan Sharpening in ENVI 5.2

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Its been a while since last time I am exploring pan sharpening. Recently I am stumbled on ENVI which had  just released version 5.3 (version 5.4 will be released around summer 2016 as far I know) and it is brings some new tools in their arsenal. One of them is NNDiffuse Pan Sharpening Algorithm. ENVI has known for very long time only have 4 common image fusion/pan sharpening algorithm (PCA, Brovey, CN, and IHS/HSV) thats not quite good to maintain spectral quality of the fusion/pan sharpening result. At later version, they are adding Gram Schmidt Spectral Sharpening which is one of the most advanced pan sharpening algorithm to date and making them equal with ERDAS (Ehlers/wavelet fusion) and PCI (UNB Fusion) as the most advanced Pan Sharpening Software. Now they are adding NNDiffuse which is the latest algorithm developed by Weihua Sun et al, NNDiffuse utilizing regression approach combined with spatial frequency extraction to generate pan sharpened dataset which not only mainta...

Download Landsat 8 Data Using Libra Development Seed

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Another platform to download Landsat-8 Data No login and registration needs, more intuitive than Glovis/EarthExplorer

Portable Basemap Server Tutorials

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Since a while ago, I have been creating some tutorials about Portable Basemap Server (PBS), an awesome tools which for some points enabling us to replace few expensive software in the online map services deployment business. For the simplicity purpose, I have been collecting all the created video tutorials into youtube playlist which could you all access thru these embedded playlist below.