Tag: animation
Moving sand in Landsat animations
by Timothy Whitehead on Dec.07, 2016, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA
Last week Google added global mosaics in historical imagery for each year going back to 1985. The mosaics are created from mostly Landsat imagery with a bit of Sentinel 2 imagery for the last couple of years (the Sentinel 2 satellite is new). The mosaics are created by gathering all the Landsat/Sentinel 2 imagery for a given year and looking for cloud-free and snow-free pixels then combining the images to create a single global mosaic for the year. Although it is fantastic for viewing long term change, the overall result is that we actually miss out on short term changes.
Back in July we wrote a post about watching sand dunes move with Google Earth imagery. Today we are looking at a similar concept, but with Landsat imagery instead. In August we created a KML file that automatically creates animations using Landsat imagery with thumbnails from Amazon Web Services. We used that tool to create the two GIF animations below:
Sand blowing in the Sahara (southern Libya). Explore original animation.
Sand blowing and irrigation circles in Oman. Note especially south west of the centre of the animation there are wisps of sand moving north west. Explore original animation.
What we found interesting is that established dunes hardly move at all over the three years covered by the animations, but loose sand can clearly be seen moving. It looks no different than sand being blown on the beach. Yet the scales involved in the animations are tens of kilometres and a three year period.
You will also notice in the second animation the dunes to the north east appear to pulse sharper, then softer again. This is because the angle of the sun affects the shadows during the course of the year.
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Animating in Google Earth Part 2 – Importing Models
by Timothy Whitehead on Nov.07, 2016, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA
This is the second in a series of posts discussing animating in Google Earth that we started last week. Today we are not looking at animation itself, but how to get a model into Google Earth that you can animate.
3D models can be obtained from a variety of sources. One resource is the SketchUp 3D Warehouse, which has a large number of models, including most of the old style 3D buildings found in the Google Earth 3D buildings layer. When downloading them, they are offered in a variety of formats, sometimes including KMZ ready for Google Earth. If that is not available try ‘Collada file’ if is available. If the only option is SketchUp file format then you will need to the free version of SketchUp to convert it to a Collada file.
There are many other sites with 3D models available such as this one. Where possible you should look for files in Collada format ( .dae file extension). Other formats can be converted but you will need to find the appropriate software first.
We found this 3D model, created by NASA, of the Mars rover Curiosity.
It is in a format used by the open source 3D modelling program Blender. So we installed Blender, opened the model then exported it to Collada format. Unfortunately, it would not immediately open correctly in Google Earth, as Google Earth’s Collada support is somewhat limited. From the KML documentation:
Google Earth supports the COLLADA common profile, with the following exceptions:
* Google Earth supports only triangles and lines as primitive types. The maximum number of triangles allowed is 21845.
* Google Earth does not support animation or skinning.
* Google Earth does not support external geometry references.
The key here is the lack of support of a feature in the Collada format called a polylist. Luckily, in many cases it is simply a matter of editing the Collada file in a text editor and replacing all instances of the word ‘polylist’ with ‘triangles’ (it is also necessary to make sure ‘triangulate’ is ticked in the export options in Blender).
We were then able to simply drag and drop it into Google Earth.
As you can see below, however, it has some purple cubes labelled ‘Don’t render’ from Blender that we don’t want.
We will have to analyse the Collada file and see if we can remove them.
Another problem we encountered is that Google Earth does not automatically zoom in on the model, and if it is very small relative to your view, when you drag the model into Google Earth it can be difficult to find the model.
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Animating in Google Earth
by Timothy Whitehead on Nov.04, 2016, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA
This is the first in a series of posts on animating in Google Earth. It is generally well known that Google Earth can display 3D models provided in KML files. Less well known is that it is possible to do basic animation in Google Earth. We have looked at a number of amazing Google Earth animations over the years, but relative to the other content for Google Earth, animations are extremely rare. There are a number of reasons for this, including a lack of good information regarding how to create these animations and easy to use tooling.
Today we are exploring the three main types of animation and their pros and cons.
In general, none of the animation methods are trivial, and almost all require some programming knowledge or custom tools to achieve a reasonable animation. Google does not provide any tools for creating animations but they do provide basic documentation for each mechanism.
Tours
Google Earth tours provide a mechanism for animating models. The animations are defined within the KML as documented here. Although KML can be typed out by hand this is completely impractical and it is necessary to have a tool that generates the KML as required.
Pros
– The person creating the tour has near complete control over what the user sees. This can be useful as it is quite easy to loose track of a moving model in Google Earth.
– Smooth animations along a line or constant rotation are handled automatically and need a lot less lines of KML than the time-based method.
Cons
– The complete control by the tour creator comes at the cost of practically no control by the user. The tour can be paused so the user can look around, but the user cannot change the view much while the tour is playing so live animations cannot be fully explored.
When to use
This is best used for models that move over a long distance that the viewer would easily lose track of. It is also ideal when you want to include other information that is best suited to being presented in a tour.
Examples
Steven Ho’s Maokong Gondola of Taipei
To see it in Google Earth, download the KML from Steven’s blog.
Captain James Cook’s exploration of Australia by Colin Hazlehurst. (not working, but you can see them on YouTube).
Time-based animations
This uses the Google Earth time toolbar in conjunction with time stamps in a KML file. The relevant KML documentation can be found here.
Pros
– This technique does not take control of the user’s view point so they are free to move around and look at the animation from different angles.
Cons
– It does not have a smooth animation feature, so smooth animations require a lot of frames, which results in very large KML files for long animations.
– The time toolbar can be confusing and users may not even realise that they must use it to view the animation. In addition, the speed of the animation is set by the user, and achieving a specific speed is difficult.
When to use
This is best suited to short, repeating animations.
Examples
The London Eye animation by Barnabu.
Turn off the Google Earth 3D buildings layer for best results.
This technique is also used for animations that do not involve models, such as the USGS animated KMLs showing earthquakes over time.
Google Earth API
This uses the Google Earth plugin. Animations can be directly controlled via JavaScript in real time.
Pros
This provides the greatest level of control and allows very complex animations.
Cons
The Google Earth API has been deprecated and could be shut down at any time. In addition, it is only supported in a few browsers (Firefox for example).
Examples
The Monster Milktruck consists of a driving simulator in Google Earth.
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‘Stabilizing’ our Landsat imagery animations
by Timothy Whitehead on Aug.30, 2016, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA
We have recently been doing a series of posts about Sentinel and Landsat imagery on Amazon Web Services (AWS), including releasing a KML file that automatically retrieves thumbnails of Landsat 8 imagery from AWS and creates animations with them.
We mentioned at the time that the Landsat images are not all perfectly aligned with each other and we had adjusted each image slightly to try and create smoother animations. To do this we used a simplified model that assumed that the imagery squares were all aligned with latitude and longitude, with up being North. It turns out that our assumptions were not valid and there was still significant ‘shake’ visible in ground features in many animations, especially those of Antarctica.
After some investigation we discovered that not only do the Landsat tiles tilt to the right as per the satellite’s orbit, but the images are placed into the thumbnails at an angle, results in further rotations overall.
The imagery on AWS is provided with a file whose name ends with MTL that contains a variety of metadata for the image. This includes the coordinates of the corners of the thumbnails (this is the whole thumbnail including the black areas). If we have two thumbnails offset from each other as shown as the red and green squares in the image below left, then in our animation we need to adjust the top of one of the images by the amount shown as the ‘top offset’. Thinking of it as purely Cartesian coordinates, to work it out in latitude and longitude it involves a series of rotations and translations, which gets rather complicated. However, we realised that instead, we could stick to proper geographic calculations, for which we already have the key routines that we worked out when working on our post on drawing circles in Google Earth. It mostly relies on an open source package called GeographicLib by Charles Karney, with a few additions also by him but not included in the main library.
Above right we see the mid-point (red circle) of the top of the red square, the mid-point (green circle) of the top of the green square, and what is known as the ‘cross track intercept’ for the green point to the thin red line. The cross track intercept is the closest point on a great circle to a location not on the circle. The distance we were looking for is from the red circle to the cross track intercept. Although this all sounds complicated, it is actually only a few lines of code, because all the hard work is done by GeographicLib. We simply repeated this for all for sides and for every frame in the animation and it worked! The animations are now much more stable even over Antarctica.
Our conclusion overall, is that although geographic coordinates can be very complicated, sometimes it is actually easier to work with them than trying to simplify things, as the heavy lifting can be done by ready-made libraries of code.
Because the thumbnails are actually higher resolution than what you can see in the popup, we have also added the ability to zoom and pan the animation. Just use the mouse scroll wheel to zoom in and out and drag the image with the mouse to pan. I am afraid we don’t have a Mac to test on, so we are not sure if this works on Mac. Let us know in the comments if it doesn’t and we will try adding keyboard controls. Remember, these are only thumbnails so don’t expect great resolution when zoomed in.
You can download the updated KML file here. We have widened the size of the popup in the standard version, but if you find it too wide for your screen, then the narrower version can be found here.
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Animating Sentinel-2 imagery in Google Earth
by Timothy Whitehead on Aug.26, 2016, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA
We have recently been doing a series of posts about Sentinel and Landsat imagery on Amazon Web Services (AWS). We created tools to let you quickly preview the latest Sentinel and Landsat imagery in Google Earth. We also looked at the coverage pattern for the Sentinel and Landsat imagery and created a way to animate the Landsat imagery. Today we are releasing similar animations for the Sentinel imagery.
To see the animations, simply download this KML file, open it in Google Earth and click on any tile.
There are several differences between this one and the Landsat animations. The sentinel thumbnails are much lower resolution than the Landsat thumbnails, so we don’t provide a link to a larger version. Also, the sentinel images often do not cover the complete tile, so we have provided an extra slider to allow you to filter out tiles based on how much of the tile they cover.
The KML file also shows with colour coding how much sentinel imagery there is, with a range from green to red for 1 to 120 images per tile and white for tiles that have over 120 images. The highest numbers can be found over Europe, which is understandable given that it is a European satellite. The amount of imagery also increases towards the north of Europe, we believe this is because the paths the satellite takes overlap more near the poles, allowing more imagery to be captured. There are also hotspots over deserts suggesting that the images are selected for low cloud cover.
The Sentinel-2A satellite that is gathering the imagery was launched in June 2015. In comparison, Landsat 8 has been around since 2013. However, the Sentinel-2A satellite covers the globe roughly every 10 days, whereas Landsat 8 takes 16 days. In addition, the Landsat 8 archive on AWS only includes selected images from 2013 and 2014 (with significantly more of the US than other parts of the world) and only has the complete set of images from 2015 onwards.
We also find the clouds look whiter and obstruct the picture more in the Sentinel imagery than they do in the Landsat imagery. This may relate to how the imagery was processed for the thumbnail or it could reflect differences in the exact wavelengths the respective satellites use to capture the colour bands.
We came across a few errors in the data, such as mislabelled tiles or missing thumbnails, but they were not significant enough to seriously affect the operation of the animations.
As with the Landsat imagery, it is important to note that this is very low resolution imagery, so expect to only see very large scale phenomena. Also, with only a year’s worth of data there is not a lot of change to see. However, it is a continuously updated service and with the expected launch of Sentinel-2B sometime next year doubling the frequency of imagery, we can expect some spectacular animations in years to come.
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Animating Landsat imagery in Google Earth
by Timothy Whitehead on Aug.23, 2016, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA
[ Update: We have updated the KML file with more stable animations and the ability to zoom in and out and pan. See this post for more details. ]
Last week we created a KML file to easily preview the latest Landsat imagery. The data comes from Amazon Web Services (AWS), which hosts a large amount of Landsat 8 imagery and also includes some handy thumbnail images. So, we have now created a KML file that automatically creates animations from the thumbnail images.
Yesterday we had a look at the coverage of Landsat 8 imagery, but we focused on how recent the imagery is. Today’s KML file instead colour codes tiles based on how many images are available. As we noted yesterday, the AWS archive is Landsat 8 imagery only and does not include all the imagery. It turns out that most of the world includes a fairly comprehensive set of imagery from 2015 onward, whereas the US (excluding Alaska) has imagery going back to 2013. The result is that most locations outside the US have about 44 scenes whereas the US typically has nearly twice as many, at about 77 scenes. Note that these figures increase with time as the data is live and a new scene is added to each tile approximately every 16 days.
To see the animations, download this KML file. Click on any coloured tile for an animation of that location. Depending on your internet speed, it may take a short while to load all the images. If you have slow internet or just want to get a quick preview of the animation, then download this KML file which uses smaller, much lower resolution thumbnails.
There are three sliders. The first slider shows the progress of the animation and allows you to manually switch between images. Doing so stops the animation, which you can restart with a button. The second slider lets you adjust the speed of the animation. The third slider allows you to filter the images by removing any with over a specified level of cloud cover.
AWS provides two thumbnails for each scene, one quite small one that we used for our ‘recent images’ KML and one much larger. We have used the larger one even though it is too large to comfortably show at full resolution in Google Earth. To see the animation running at full size, click the link at the top right of the animation window.
Remember that Landsat imagery is very low resolution (about 30m per pixel) and these are just thumbnails, which are even lower resolution than that. So expect to only see very large scale changes. Look for changes in seasons, ice cover changes near the poles, lakes shrinking or growing, and even sand dunes moving.
A major problem is the large amount of cloud cover in the images. If you select only scenes with minimal cloud cover you end up with only a few images to work with. This highlights just how difficult it is for commercial providers to get good imagery.
One problem we had was that the images are not captured from exactly the same angle, so there was a significant amount of shaking in the animations. We have tried to fix this by reading the latitude and longitude metadata included with the scenes and moving the individual images appropriately. It is still not perfect as a browser cannot position an image at sub-pixel resolution.
Let us know in the comments if you find anything particularly interesting. Ideally tell us the path and row.
Here is an interesting tile in Chad that shows some fire scars.
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Animating Lusaka, Zambia
by Timothy Whitehead on May.25, 2016, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA
We were recently having a look at the historical imagery of Lusaka, Zambia, and we noticed that there is a lot of historical imagery for the last two years. There is an image nearly every week. Lots of historical imagery provides the ideal opportunity for animations, so here are two that we tried out.
The first animation uses about one image per month for two years. The idea was to try and show the changing of the seasons.
The second shows a shopping mall (East Park Mall) being built. It consists of 134 images captured almost weekly.
You can adjust the speed of the animations by dragging the slider below each animation.
It would be nice if Google Earth could do this sort of animation natively. It is possible to create a tour with historical imagery and we have in the past created tools to help do this. However, Google Earth cannot animate faster than about one image per second and that is really too slow for the above animations to look good. For comparison you can download the two tours here. Unless you have fast internet it could take a while for all the images to load and require a lot of download data.
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Celebrate Chinese Spring Festival in Google Earth
by Timothy Whitehead on Feb.23, 2016, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA
Here at GEB we have traditionally celebrated the new year with a Google Earth fireworks animation created by Steven Ho. This past new year we decided to expand on the idea by allowing you to create fireworks at the coordinates of your choice. This, in turn, has inspired Steven Ho to create a new animation to celebrate the Chinese Spring Festival, (also known as Chinese New Year or Lunar New Year).
His animation shows Chinese couplets falling from the sky, with the camera slowly rotating around the location you select – all set to music. Chinese couplets are a popular form of Chinese poetry that consists of a pair of lines of verse that match up in a number of different ways. You can learn a bit more about them on the Wikipedia page. They are popular for decorating doorways and also often used during celebrations, such as the Chinese Spring Festival.
He has also created a similar animation for the Taiwan Lantern Festival, which shows lanterns flying up into the sky at night.
To see YouTube videos of both animations and create animations for the location of your choice, see the full post on Steven’s blog.
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Seeing imperfect orthorectifcation in Google Earth imagery
by Timothy Whitehead on Oct.20, 2015, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA
Yesterday we talked about orthorectification and how it is imperfect, especially when using an inaccurate terrain model. We thought we would have a look at the effect using historical imagery. We used a variation on two JavaScript tools we have created in the past for animating historical imagery using the Google Earth plugin and using Google Earth Tours. This enabled us to create tours which animate only a selection of historical imagery and exclude lower quality images. Because Google Earth does not allow us to play the tours at a reasonable speed (it omits images), we recorded the tours and then sped up the recording.
We chose three locations that we know have significant elevation variation as well as a lot of satellite imagery. They are Devil’s Peak, Cape Town, South Africa, Rio de Janeiro, Brazil, and Calama, Chile.
If you look carefully, you can see that some locations move more than others.
The buildings at 1 and the bridge at 2 seem to move much less than the surrounding imagery. This suggests that the terrain model for these locations is closer to the true altitude than for surrounding areas.
You can download the Google Earth tours we used to create the video here.
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Animating historical imagery using Google Earth Tours
by Timothy Whitehead on Jul.30, 2015, under 3D Models, Argentina, Australia, Brazil, California, Denmark, England, Germany, Google Earth News, Google Earth Tips, Google Sky, Google maps, Hawaii, Indonesia, Ireland, Italy, Japan, Kenya, Mexico, Natural Landmarks, Netherlands, Sightseeing, Street Views, USA
Last year we showed you how to animate Google Earth historical imagery using the Google Earth plugin. However, the Google Earth plugin has been deprecated and is set to stop working on December 12th, 2015. In addition, Google Chrome and other browsers are making it harder to use the plugin.
So, we have decided to try and achieve the same thing using Google Earth Tours. In a Google Earth Tour it is possible to specify particular views that include not just the position and angle, but also whether or not to show ‘historical imagery’ and when in ‘historical imagery’ what exact date to show. It is, however, not easy to create a Tour to animate historical imagery using just the built in functionality of Google Earth, so instead we have decided to do it via JavaScript.
To use it, the first step is to decide what view you want in Google Earth. Create a Placemark in Google Earth then save it as a KML file. Do make sure it is KML not KMZ, as our script cannot read KMZ. Next, decide on your settings below and and upload the Placemark file. Then click on the “Create Tour” link to download the generated KML tour for you to view in Google Earth.
It has been tested in Google Chrome, Firefox and Internet Explorer 11.
Start: | (yyyy-mm-dd) |
End: | (yyyy-mm-dd) |
Step: | |
Pause: | (seconds) |
Placemark KML: |
Try adjusting the settings to get the best results for a given location. Remember that the functionality works whether you want to see whole continents or zoom right in, but you will want to choose your settings depending on the availability of imagery. Although it is possible to make the pause between steps shorter than 1 second, we found that Google Earth could not keep up and simply did not refresh the screen on every step. It seemed to work alright with the 1 second setting, but if you have a slow computer or slow internet you may want to make it longer. For best results run the tour through a few times depending on the speed of your internet to cache the imagery.
We have created a few tours which you can download here to give you an idea of what is possible.
The historical imagery for Europe in the YouTube video above appears to come in waves from the top downwards. We believe this has more to do with how Google Earth refreshes the screen during the tour than the actual dates that the imagery was added.
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