Terra Server - Aerial photography

Terra Server, a division of PrecisionHawk, is a website where you can browse online aerial images and maps. You can search online for satellite & aerial images. View for free and purchase digital copies, prints, and licences.

Didn't find what you were looking for? Now you can Order New Satellite Imagery!

Terra Server can capture new, high resolution imagery of any location on Earth using the world's most advanced commercial satellites. Options include visual, multispectral, and radar imagery.



The company can help you acquire new, high resolution satellite imagery of any location on Earth using the world's most advanced commercial satellites. Visual, multispectral, and radar imagery available.

Or, if you're interested, they can perform a comprehensive search to help you find and acquire recent and historical satellite and aerial photos from the 1930's to 2015.


The company's membership products and services feature:

• Membership
• New Imagery Acquisition
• Recent & Historical Imagery
• Licenses
• Maps
• Digital Images / Downloads
• Prints & Posters
• Global Basemap
• Digital Elevation Models
• Vegetation Data
• Big Data Analytics
• Consulting

For more information and querries you can visit the company's webiste by clicking here.

Satellite imagery updates for 2015

For the first half of 2015, as it has in the past, Google released imagery update maps showing outlines of newly updated imagery. However, in June, it released the Voyager layers, which include a ‘satellite imagery updates’ layer. We believe the change was made due to the deprecation of Google Maps Engine, which is what was formerly used to publish imagery update maps. However, the Voyager layer has only been updated once since June, so we have mostly been relying on the Google Earth API to find imagery updates. See here for our imagery update posts of 2015.

We have used the Google Earth API to create an approximate map of the areas in Google Earth that currently have imagery dated 2015.

To see the above map in Google Earth download this KML file.

The USA, parts of Europe, and Japan got quite a lot of aerial imagery. Most of the rest of the world got satellite imagery concentrated on areas with high population. Interestingly, the southern and eastern countries of Asia got remarkably good coverage.


Also of note, is that Syria and the Ukraine seem to have been added to the list of countries with blanket censorship. There were no satellite imagery updates with imagery dated 2015 in Syria, the Ukraine, Afghanistan, or Iraq. Both Syria and the Ukraine did receive imagery during 2015 but it was dated 2014. It is not Google carrying out the censorship but has most likely been done by buying rights to the imagery from the satellite imagery providers. The censorship in Ukraine was implemented long after the conflict there started and we have seen imagery taken after flight MH17 was shot down over the Ukraine. The most recent imagery appears to be from November 2014. At the same time, the Ukraine got Street View in October 2015, so although it is censored from above much of it is now more visible from ground level.

It must be noted that Google has not yet added any December imagery, and in general Google’s imagery updates often include imagery of various ages, so the amount of imagery dated 2015 will increase with time.


About Timothy Whitehead
Timothy has been using Google Earth since 2004 when it was still called Keyhole before it was renamed Google Earth in 2005 and has been a huge fan ever since. He is a programmer working forRed Wing Aerobatx and lives in Cape Town, South Africa.

Source: Google Earth Blog

Seeing a tornado track with Landsat imagery

We have looked at the paths of destruction caused by tornadoes in Google Earth imagery a number of times before. Nearly every one of the tornadoes we have looked at in the US occurred in the months of April or May, which appears to be peak tornado season in the US. Tornadoes can, however, occur at any time of year and due to the unseasonably warm weather the US has been having recently there were several tornadoes just before Christmas.

We came across this story, which says that one of the tornadoes had a record long track for the month of December. Google has not yet released any December imagery so we wondered if it would be visible in Landsat imagery. We used the technique described in this post to get a relatively low resolution Landsat image of the area captured on December 24th, the day after the tornado struck and found we were able to just make out the path of the tornado. We also downloaded the higher resolution version of the Landsat data and processed it with software from GeoSage as described in this post.


We were able to trace out the path of the tornado a distance of around 92 km (57 miles). News reports, however, mention damage to property quite some distance from both ends of the visible track (from Clarksdale, Mississippi to Lutts, Arkansas) reaching at least double that distance.

A section of the track as seen in Landsat 8 imagery. Can you see it?

Keep in mind that Landsat imagery has a resolution of about 30m per pixel. The visible track of the tornado is over a kilometre wide in places.

Shown above is only a part of the visible track. For the full track and two different versions of the Landsat imagery (cropped and compressed to keep the file sizes down) download this KML file. The KML also includes markers relating to some news stories and links to YouTube videos of the tornado or other tornadoes in the vicinity.

About Timothy Whitehead
Timothy has been using Google Earth since 2004 when it was still called Keyhole before it was renamed Google Earth in 2005 and has been a huge fan ever since. He is a programmer working forRed Wing Aerobatx and lives in Cape Town, South Africa.

Source: Google Earth Blog

Line of Sight: Track the Real Time Locations of Satellites

BY ELIZABETH BORNEMAN



Humans have had the ability to send objects into space since the beginnings of the 20th century. The first satellite was launched in 1957, the famous Russian Sputnik I was followed by the launching of satellites of American and global origin. Today there are over 2,250 satellites surrounding the Earth, orbiting this incredible planet in silent consistency.

Satellites literally surround us. Not only are they up in the sky above us, but their influence allows us to conduct our lives as usual. Satellites beam our wireless networks, allow us to communicate, and transmit important information from one place to another. We rely on information from satellites to get our phone signal, to send a picture, and to gain information about the world around us.


Despite all this, satellites don’t always have a big visual impact on how we live our lives; they are abstract, in space, silent and often invisible entities. Now, however, we have the ability to see satellites from the comfort of our own homes.

Line of Sight is an online map application that tracks where each and every satellite is above the Earth in real time. The map was created by Patricio Gonzalez who is part of the open-source mapping startup company Mapzen. Patricio Gonzalez is a resident artist and engineer at the project who wanted to bring satellites and their existence a little closer to home.

With the Line of Sight map users can track satellites that fly above their homes and cities with just the click of a button. Gonzalez used data on satellites from various tracking companies to set up his map, which can tell you where and when satellites will pass over certain places. Satellites can move at approximately 17,000 miles an hour, but they can still be seen orbiting in space with the naked eye on a clear night.



Line of Sight tracks active and dead satellites as well as sizeable bits of space junk that continue to orbit consistently around the Earth. Parts of rockets can be seen, as can other pieces of space debris caught in the Earth’s gravitational pull. If you are curious about satellites and other objects orbiting around the Earth, Line of Sight provides more information about what you can see in the night sky above you. Check it out if you have the chance and be amazed at what is just above us in the sky.

Source: GIS Lounge - Maps and GIS

Case study: Chennai Silver Lining – A Community Sanitation Planning Using GIS

We talked about recent flooding and using GIS for emergency relief with one of the volunteers for the Chennai Silver Lining – A Sanitation Drive project. We bring you a story about great community initiative of Chennai’s citizens who decided to reduce the health risks of flooding to Chennai’s population.

The Project
A group of volunteers led by Mr. Sai Shankar decided to initiate Chennai’s Silver Lining project after the heavy rainfalls from Nov 30 to Dec 2 2015, which caused severe flooding that poses significant health risk for the Chennai Population. They wanted to prevent the post-flooding epidemic breakout by reaching out to every corner of Chennai with a 7 days action plan, to sanitize the water deluged area with bleaching powder. Chennai Silver Lining project needed over 100 volunteers in different parts of a district. They used guidelines about post-flood emergency health precautions – community sanitation from Disaster Management Education Planning & Training (ADEPT). The idea was to prevent outbreaks of diseases like typhoid, dysentery, infectious hepatitis, and other diseases associated with floodwaters.


Cleanup Procedure
Cleanup procedures include using sanitizing agent such as hypochlorite in the form of bleaching powder or commercial household bleach, which is the most widely accepted, safe and effective sanitizing agent. Hypochlorite is used for eliminating bacteria, viruses and fungi during the cleanup process. It is important not to waste any time during a flood relief, because pathogenic organisms will not become airborne as long as the surfaces they have contaminated remain wet. They can enter the body and cause disease through water splashing into the mouth, mucous membranes, open cuts, etc. Once dried, organisms can be spread on dust particles by air movement. Therefore, it is important to “sow” bleaching powder into all wet and marshy areas and bring all contaminated surfaces into contact with bleaching powder as soon as possible. Volunteers needed to act quickly and those with experience in GIS decided to use cloud based mapping solution for the sake of fast and effective team coordination. They used GIS Cloud’s Map Editor to create HUB points with location name, address and contact number in the map. Later, this map was published with GIS Cloud’s Map Portal so that it would be accessible to wider public and volunteers.

Chennai volunteers were motivated to create Silver Lining project after they have studied the after-effects of flooding and decided to help their community by organizing themselves to help with the flood relief. They have organized 13 HUB stations, marked on a map, for different areas of Chennai and conducted the project with the help of Chennai’s community. The full number of volunteers and percentage of area sanitized still isn’t available, but project participants claim that Chennai Silver Lining achieved a community based success that proved the strength of a unity in extreme circumstances.

Importance of Good Preparedness for the Future

This project offers a good example of a community-based initiative that highlights the importance of spatial thinking in disease prevention. Roots of using spatial thinking in risk management in the case of disease date to 19th century when Dr. Snow used a map to find the source of cholera outbreak. In the 21th century, we have various web mapping tools which can do the same, and more. Chennai Silver Lining project volunteers agreed on importance of education for encouraging the spatial thinking of students, policy-makers, government and NGOs, because “prevention is better than cure.” In this case, GIS proves to be a great decision-making tool that can be used for any risk and mitigation plan.

They believe that GIS can be extensively used to re-survey the complete LU/LC of Chennai district and make it as a digital copy. Volunteers would like the Metropolitan authorities to have this map for future decision-making and coordination activities, initiating research and development in the National Disaster Management. This map should be available to the public, being a good start in encouraging spatial thinking for all the people.

Chennai Silver Lining project serves as an exemplar case for both GIS and non-GIS experts that want to do something for their community by applying spatial thinking and spatial knowledge to a concrete project or a cause. Cloud-based GIS tools are a great way for the volunteers in different initiatives to organize themselves, collaborate and improve their decision-making with the help of technology. You can see Chennai volunteer’s map here.

Source: Geoawesomeness and GIS Cloud