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Google Earth FAQ
- What is Google Earth?
- Google Earth is a desktop mapping application freely distributed by Google. Although the free version of Google Earth is not a GIS application and hence it doesn't provide geoprocessing functionality, it is a very convenient way to visualize marine surveys' data and it's fun!
Download Google Earth (open a new window)
- What is KML/KMZ files?
- A kml file is a kind of XML document designed to supply geographic information to Google Earth. Google Earth loads a kml file and maps geometry features contained in the kml file on 3D Earth.
Below is a sample kml representing a point geometry.
<Placemark>
<visibility>1</visibility>
<name>283 #1</name>
<description><![CDATA[(lon, lat): (-72.617, 39.25)]]></description>
<Point>
<altitudeMode>clampedToGround</altitudeMode>
<tessellate>1</tessellate>
<coordinates>-72.617000, 39.250000, 0</coordinates>
</Point>
<LookAt>
<longitude>-72.617000</longitude>
<latitude>39.250000</latitude>
<tilt>0</tilt>
<heading>0</heading>
<range>10000</range>
</LookAt>
<styleUrl>#default</styleUrl>
</Placemark>
A kmz file is a compressed kml file. This is useful to reduce data transfer time when the kml file gets very large in size. Essentially a kmz file is a zipped file with .kmz file extension, so you can use any zip utility (you may need to change the extension from .kmz to .zip). To load a kmz file to Google Earth, you don't need to umcompress it. Google Earth handles it.
OBIS-SEAMAP automatically creates kmz files when kml files get larger than 5 MB.
- How do I load a dataset into Google Earth?
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- After finding a dataset you are looking for, click the link saying something like "Google Earth".
- When the following dialog shows up, click "Open".
- Google Earth will be launched and the kml file produced by OBIS-SEAMAP be loaded.
- When I have loaded a dataset into Google Earth, the labels and icons are too large to distinguish each points. How can I adjust the label/icon sizes?
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- Right click on a folder or an individual point and select 'Edit...'.
- Check 'Advanced' on, if not yet checked.
- Click on 'Scale...' for labels or icons to show a scaling bar and move it up or down to adjust the size.
- Is there a way to adjust the transparency of SST layers?
- Select the layer and you'll see the transparency bar at the bottom of 'Places' area (just above 'Layers' area). Slide the bar left or right to adjust the transparency.
- Downloading a KML may take a long time. Is there a way to save it locally so I don't need to access your web site to get the KML.
- When you are asked to open or save the KML file, save it to a local folder. Then open the KML file with Google Earth. In this way, you can load the data without downloading it every time. However, you may need the Internet connection regardless of the locally stored KML if some resources (icons, SST images) are not cached locally. In addition keep in mind that data might be updated in the future. Downloading a KML file always gives you the latest data.
- Whenever I try to view a certain dataset with a number of points, it crashes Google Earth. Is there a limit regarding the number of points that can be viewed with Google Earth? How can I work this around?
- We tested some datasets with more than 10,000 records and assured Google Earth could show them in a certain envirnment. This means in another environment, it couldn't. It will depend on your computer settings and resources. One tip we've learned is that OpenGL seems to be more stable than DirectX. So try to switch 'Graphic Mode' to OpenGL if you have a trouble viewing a certain dataset.
Created by
admin
Last modified
2006-01-25 04:42 PM
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