Multiple shapefile export to kml

Turning Shapefiles into Google Earth Goodness: A Human’s Guide to KML

Okay, so you’ve got a bunch of shapefiles – those trusty workhorses of the GIS world. But what if you want to share that geographic data with, say, your non-GIS friends, or just visualize it in the oh-so-accessible Google Earth? That’s where KML comes in. Think of it as the universal translator for geospatial data, making it easy to display your maps in Google Earth and Google Maps. Converting a single shapefile is easy enough, but what about multiple shapefiles? Don’t sweat it. This guide will walk you through the process, sharing tips and tricks I’ve picked up along the way.

Shapefiles and KML: A Quick Refresher

Before we dive in, let’s quickly recap what these formats are all about. Shapefiles, developed by Esri, are like the organized filing cabinets of the GIS world. They store spatial data as points, lines, and polygons, along with all sorts of descriptive information. A single shapefile is actually a collection of files (like .shp, .shx, and .dbf) working together.

KML, on the other hand, is more like a friendly tour guide. It’s built on XML and designed specifically for displaying geographic data in applications like Google Earth. KML files can also represent points, lines, polygons, and even images. You’ll usually find them with a .kml or .kmz extension (the latter being a zipped, compressed version).

Making the Magic Happen: Converting Your Shapefiles

Alright, let’s get down to business. There are several ways to convert those shapefiles to KML, each with its own strengths and weaknesses. Here are a few of my go-to methods:

1. ArcGIS Pro: The Pro’s Choice

If you’re already using ArcGIS Pro, Esri’s flagship GIS software, you’re in luck. It offers a pretty straightforward way to get the job done. The trick is to first group your shapefiles.

• Grouping is Key: In ArcGIS Pro, select all the shapefiles you want to convert in the “Contents” pane (hold down Ctrl while clicking). Right-click and choose “Group.” Boom! You’ve created a group layer.
• The “Layer to KML” Tool: Now, head over to the “Geoprocessing” pane and search for “Layer To KML.” This tool is your new best friend. Select your newly created group layer as the input.
• Tweak and Run: Give your output KML file a name and location, play around with the other settings if you’re feeling adventurous, and hit “Run.” Easy peasy.

2. QGIS: The Open-Source Hero

QGIS, the free and open-source GIS powerhouse, is another excellent option. It might take a little more elbow grease, but it’s totally doable.

• Merge and Conquer: One approach is to merge all your shapefiles into a single file before converting. Use the “Merge Shapefiles to One” tool (you’ll find it under “Vector > Data Management Tools”). Then, right-click on the merged layer, select “Export > Save Features As…”, and choose “Keyhole Markup Language (KML)” as the format.
• The Individual Route: Alternatively, you can convert each shapefile to KML separately and then manually combine them in Google Earth. This can be handy if you want more control over the individual layers.

3. Global Mapper: The Conversion Specialist

Global Mapper is a commercial GIS software that’s known for its impressive data conversion capabilities. Honestly, it often feels like it was built for tasks like this. If you’re dealing with a ton of conversions regularly, it might be worth checking out.

4. Online Converters: Quick and Dirty (Sometimes)

Need a super-fast solution? There are several online converters out there, like MyGeodata Cloud, that let you upload shapefiles and spit out KML files. These can be great for one-off conversions, but be cautious about uploading sensitive data to third-party sites.

5. Python Scripting (QGIS): For the Coding Crowd

If you’re comfortable with Python, you can automate the whole process with a script in QGIS. This is the ultimate power-user move, allowing you to batch convert dozens or even hundreds of shapefiles with a single command.

Things to Watch Out For (and How to Avoid Them)

Converting shapefiles to KML isn’t always a walk in the park. Here are a few potential pitfalls and how to steer clear of them:

• Coordinate Systems: The WGS84 Rule: KML files like to play by their own rules, and that means using the WGS84 coordinate system (EPSG:4326). If your shapefiles are in a different system (and they very well might be), you’ll need to reproject them before converting. Luckily, both ArcGIS Pro and QGIS have tools for this.
• Attribute Overload: Make sure you’re only exporting the attributes you actually need. The more data you include, the bigger (and slower) your KML file will be.
• Size Matters: Keep it Lean: Speaking of file size, large KML files can bog down Google Earth. Simplify your geometries (reduce the number of vertices) and use KMZ (compressed KML) to keep things running smoothly.
• Geometry Clashes: When merging shapefiles, make sure they all have the same geometry type (points, lines, or polygons). Mixing and matching can lead to unexpected results.
• Shapefile Quirks: Shapefiles have some old-school limitations, like short field name lengths (10 characters) and attribute size limits (4,000 bytes). These can sometimes cause issues during conversion.
• Data Loss Blues: Keep in mind that KML doesn’t support all the fancy features of shapefiles, like subtypes and geometric networks. Converting to KML might mean losing some of that extra data.

Pro Tips for KML Conversions

Want to become a shapefile-to-KML ninja? Here are a few extra tips I’ve learned over the years:

• Always Reproject: Seriously, always reproject to WGS84. It’ll save you headaches down the road.
• Simplify, Simplify, Simplify: The simpler your geometries, the faster your KML file will load.
• Be Attribute-Conscious: Only export the attributes you absolutely need.
• KMZ is Your Friend: Compress those KML files!
• Validate Your KML: There are online tools that can check your KML file for errors.
• Know Your Limits: Be aware of the limitations of both shapefiles and KML, and plan accordingly.

Final Thoughts

Converting multiple shapefiles to KML might seem daunting at first, but with the right tools and a little know-how, it’s totally achievable. Whether you’re sharing data with colleagues, creating interactive maps for the public, or just exploring your own geospatial data in Google Earth, KML is a powerful format to have in your toolkit. So go forth, convert your shapefiles, and unleash the power of Google Earth!