Thursday, September 18, 2014

Where are my streets Chrome? Google Maps bug on Chrome or vice-versa

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I was checking the route for nearest police station from my office around 3 PM MT using the Chrome. The  Google Map's street looks so funny and floppy. All the street lines and highways lines were wiped out. The interstate has some brown points, if you zoom in them the point looks like half circle. Which has the bug Google Maps or Chrome? Click on images for bigger picture !

(Missing roads)

                                                                 (Missing roads on zoom)

                                                                         (More zoom in...)
(Looks good in  the Firefox though)

Thursday, November 21, 2013

Impact of Google Maps API v2 shutdown on Openlayers base layers and a easy solution

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Finally on Nov 19 2013, Google shut down Google Maps v2 API, which was depreciated in May 19 2010 but was working continuously Nov 19. I was aware of version depreciation, but I procrastinate to upgrade till last minute because of working on too many other things. While checking my Web map (built on Openlayers, Geoserver and Google Maps as base layers (Google Maps API v2) on Nov 20, I saw two map controls one from Openlayers and other from Google Maps API also noticed that map application was unresponsive.


Looking around I found easy steps to fix it without major change in the code-

Thursday, January 17, 2013

Geospatial data Mashups with Google

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Abstract
Analyzing space-time variation is common in Geography. Appropriate geo-spatial visualization enables us to understand data in a precise manner. There have been numerous researches, tools, and methods in pursuit of a better visualization method for geospatial data. Here we present the sets of examples developed by us to show the benefits of the web cartography using Google Earth/Google Maps mashups to display geospatial data. Moreover, we include the practical implication of applications that are useful for visualizing geospatial world.

Tuesday, January 8, 2013

Geographic Visualization for the Web : Book Review

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This book is an attempt to share the knowledge I've gained from the experts at Google. When I joined it, the KML team consisted of two engineers: Bent Hagemark and Michael Ashbridge ("Mash"). Bent and Mash's mission was to corral the existing KML into a formal XML schema, to create compelling examples that would represent good coding style, and to shepherd the language to its new and deserved status as an international standard. I was to create a website for KML and expand the existing documentation. I managed to complete that task, but it always felt as though I'd exposed only the tip of the iceberg. Well, here's The Iceberg.”          – Author

"KML Handbook :Geographic Visualization for the Web" is primarily targeted for people who are curious about how to create customized presentations for an Earth browser such as Google Earth but have little or no experience with computer programming. It has step by step guidelines to create and customize Google Placemarks and Ballons, Google Earth Overlay, Static and dynamic KML/KMZ update and manipulation.

Pro: This  book has  a step by step guide to writing and using KML programming language to produce enhanced graphics as overlays onto web based mapping programs such as Google Earth. You do not need to have any programming skills to use this book except basic knowledge of HTML and XML.

Con: Some images in the books are fuzzy and hard to read. It is highly Google centric, may be because the author, Josie Wernecke, senior technical writer at Google.



Wednesday, November 23, 2011

Instructions for Creating KMZ Image Overlays from ArcGIS in Google Earth and Google Map

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Creating a kmz image overlay

 1. Make sure the dataset you are working with has a geographic coordinate system (unprojected) with WGS84 as the datum. If not, you will need to reproject your data. If the coordinate system of your datasets is defined you can change the projection “on-the-fly”. To reproject on-the-fly, go to Layers then Click Properties and specify geographic with WGS84 datum as the coordinate system. However, I recommend reprojecting the actual GIS datasets (shapefiles, grids, etc.) because project-on-the-fly is not always very precise, particularly when dealing with datum transformations.

2. Switch to the layout view. Select a layout that matches the dimensions of your map as closely as possible. To keep the file sizes of your images small, try to leave as little empty space around the edges as possible. Right-click on the layout and select Page and Print Setup to change the layout size.

3. Right-click on the map and select Properties. Go to the Size and Position tab. Under Size, set the Width and Height to exactly match the Width and Height of your layout. Under Position, set X and Y both to zero. Go to the Frame tab and make sure that Border is set to .

4. Zoom and pan in the layout so that you have as little empty space at the edges as possible.

5. Right-click on the layout and select Properties. Go to the Data Frame tab. Under Fixed Extent, you will see the latitudes for the top and bottom of the current layout, and the longitudes for the left and right sides of the current layout. Write these numbers down or cut and paste them into a file. Do not change them!

6. Go to File then Click Export Map. Export the tile as a PNG image. Select the Resolution (in pixels per inch). Depending on the amount of detail in your map and the size of your layout, you may need to experiment with a variety of resolutions to achieve a good balance between image quality and image size. 200 pixels per inch is often a good place to start. On the Format tab set Color Mode to 24-bit True Color, set the Background Color to white, and set the Transparent Color to white as well. If you have white in your map, you may need to choose a different shade (perhaps grey) for both the Background Color and Transparent Color. Do not check Clip Output to Graphics Extent. Click Save to export your file.
7. Open Google Earth

8. Select Add then Click Image Overlay

9. In the New Image Overlay box, type in a name for your overlay and use the Browse button to link to the image that you exported. You can use the Transparency slider to adjust the opacity of the overlay. Add a Description if you like.

10. Go to the Location tab and type or paste in the boundary coordinates of your layout that you saved in step 5. Be sure to include the negative sign for west latitudes. Click on OK.

11. You should see the name of your new image overlay under your Places in Google Earth. Right-click on it and select Save Place As… to save it as a kmz file. Once you have saved the kmz file, you can delete the temporary image overlay. You can double-click on your kmz file to open it in Google Earth,or use File then Click Open from the Google Earth menu.

Modifying a kmz image overlay

 1. You can use a program such as 7-zip to open the kmz archive. Inside you will find a KML file entitled doc.kml, and a subfolder that contains your image. You can open the KML file with a text editor. Note that there are just a few tags here that tell Google Earth what to do with your image. There is a tag. The tag has a code that specifies the amount of transparency in the overlay. The tag identifies the image to be overlaid. Thetab identified the bounding coordinates of the image.

2. You can create new kmz files by modifying this existing file. You can make a copy of the existing KMZ file, use 7-zip to remove the image1.png image and replace it with a image2.png image, and then use a text editor to modify the and tags in the kml file. Even if you have a new image has different bounding coordinates, you can edit them directly in the kmz file rather than using the New Image Overlay tool in Google Earth.

3. You can also add a legend or other graphics as screen overlays that are attached to a particular location on the screen (for example, the lower left corner) rather than a particular geographic location on the Earth’s surface.

4. There are various ways to export a legend from ArcGIS to a PNG file. One approach is to export the legend as part of a larger map graphic and then clip it out using a graphics program. Alternately, you can “trick” ArcGIS into letting you export the legend directly. Make sure your map symbology is set up the way that you want it displayed in the legend (it should match the map graphic that you have already exported). Set up your layout dimensions to match the size of your exported graphic (e.g., 1.5 x 1.5 inches). It can help to Insert then Click Legend into your layout first to get an idea of its dimensions. Your legend should fill up the layout and leave minimal whitespace at the edges. Right-click on the legend and choose Convert to Graphics. Then you can uncheck the map layers in the Table of Contents and you will only see the legend. You can now export the layout to a PNG file like you did with the map image. The only difference is that you should set the Background Color to white and the Transparent Color to No Color.

Wednesday, July 13, 2011

Google Earth Engine API : An ambitious Project

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A highly ambitious project by Google, Google Earth Engine, will be launch by  the end of 2011. This project is using high resolution images from more than 30 earth observing satellites such as Landsat, MODIS, IKONOS, QuicBird etc to build global archive of atmospheric corrected data sets. According to Earth Engine team, these archives will be"available online with tools for scientists, independent researchers, and nations to mine this massive warehouse of data to detect changes, map trends and quantify differences on the earth's surface" in a cloud computing platform. 


Currently, this project is in testing phase with limited  access to few groups of partner including CLASlite and IMAZON.  Let us wait and see how far they can go !!!

Sunday, June 12, 2011

Custom Google Maps Style

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From last couple of days I was busy on Google custom styling like http://maps-api-tt.appspot.com/apilite/styled/styled.html .

Fortunately, I found a good tutorial to share to carry out such custom styling. Check it out @bestfromgoogle  

Wednesday, May 25, 2011

Choropleth mapping techniques for Web2.0

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For my recent project, I have to display county wise time series data of disease pattern in web map for the conterminous United States for 20 years. In addition, I have to use Google maps as base layer and should overlay images on the top of it.  The concept sounds easy, and it was also similar with choropleth or thematic mapping. However, it should be in the Web 2.0.

I tried to figure out what are the possible ways to achieve this, I tried and few of them. Here I am going to share the pros and cons of these methods in a real quick and dirty style.

Choropleth with GFT
1) Google Fusion Tables

Pros:
Easy, No understanding of computer programming needed. Upload small or large data sets from spreadsheets or CSV files. Visualize your data on maps, timelines and charts. Pick who can access your data; hide parts of your data if needed. Merge data from multiple tables.

Cons:
Not much flexible and you can’t tweaks easily according to your needs. 

Choropleth with Cartographer.JS and Google API
2) Cartographer.js and Google API

Pros: It generates choropleth maps directly from database or other standard data handlers. Fast for small area mapping.

Cons:
Understanding of JavaScript is needed. It supports only US (County and State level data). I got performance is worst if we map entire 50 states. I recommend it to use to map few states only. Although cartographer.js's documentation claims browser friendly, it is horrible with IE, works so so with Firefox and chrome. 

 

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