OpenStreetMap

Up-to-date open data imagery - it is available, use it!

Posted by imagico on 20 July 2016 in English (English)

Last week BushmanK wrote about the use of up-to-date open data satellite imagery for mapping in OSM and noted what i also frequently experience - that awareness and interest within the OSM community regarding the large bandwidth of up-to-date near real time open imagery that is available today is astonishingly very low. Mappers do complain that imagery in Bing and elsewhere is frequently outdated and poor quality but few are aware that newer imagery exists and is available and in contrast to Bing etc. is often truly open data.

The real problem here is that as a result of this mappers keep wasting energy and time on tracing things from images that are hopelessly outdated and at the same time often also poorly aligned. At the moment approximately 15-25 percent of the Earth land surfaces are shown in Bing and Mapbox with 15 year old imagery that is poor quality in a lot of aspects.

With this blog entry i hope to somewhat further increase awareness of this subject among mappers. I have been for quite some time making available recent imagery from open data sources for mapping in OSM. This is only a small contribution for select areas but shows that a huge body of primary data is available today and is largely unused for OSM-mapping.

Here a list of the most recent additions - you can find the full set of images currently available on the OSM images for mapping and some more details in various blog posts:

satellite image samples

Northern Greenland July 2016

Images from 2016-07-17, the most recent ones of this remote area, better detail and more up-to-date than current mapping in OSM.

tms:http://imagico.de/map/osmim_tiles.php?layer=ls_polar2&z={zoom}&x={x}&y={-y}

http://maps.imagico.de/#map=7/83.190/-34.761&lang=en&l=ls_polar2&r=osmim&o=3&ui=8

Northern Ellesmere Island July 2016

Images from 2016-07-08 to 2016-07-15, recent images, partly overlapping the previous, poor and largely faulty data there in OSM based on imports.

tms:http://imagico.de/map/osmim_tiles.php?layer=nellesmere_ast_2016&z={zoom}&x={x}&y={-y}

http://maps.imagico.de/#map=8/82.699/-73.641&lang=en&l=nellesmere_ast_2016&r=osmim&o=3&ui=8

Vostochny Cosmodrome

From 2016-06-23, showing most recent building activities.

tms:http://imagico.de/map/osmim_tiles.php?layer=S2A_R089_N52_20160623T024048&z={zoom}&x={x}&y={-y}

http://maps.imagico.de/#map=12/51.823/128.234&lang=en&l=sat&r=osmim&o=3&ui=8

Panama Canal

From 2016-06-07 - the new locks.

tms:http://imagico.de/map/osmim_tiles.php?layer=S2A_R111_N09_20160604T154554&z={zoom}&x={x}&y={-y}

http://maps.imagico.de/#map=14/9.287/-79.919&lang=en&l=sat&r=osmim&o=3&ui=8

Darwin and Wolf islands, Galapagos

From 2016-03-11 - two small islands with poor coverage in other sources.

tms:http://imagico.de/map/osmim_tiles.php?layer=S2A_R040_N01_20160311T164128&z={zoom}&x={x}&y={-y}

http://maps.imagico.de/#map=11/1.556/-91.940&lang=en&l=sat&r=osmim&o=3&ui=8

Batam, Indonesia

From 2014 to 2016, quite a few islands missing or poorly mapped in OSM just a short distance from Singapore.

tms:http://imagico.de/map/osmim_tiles.php?layer=LC81250592016107LGN00&z={zoom}&x={x}&y={-y}

http://maps.imagico.de/#map=10/0.699/104.490&lang=en&l=sat&r=osmim&o=3&ui=8

All of these are prepared from open satellite data, of course the main advantage of this is you do not depend on my or others’ services to make use of it. Processing raw satellite data is something you need to learn to do it but it is not that difficult in principle. You just need time and an open mind to get the necessary experience and some background in photography or color physics definitely helps. There are quite a few mappers who routinely map from custom processed Landsat images for example.

And since the remark will inevitably arise - yes, these are all lower resolution than what is necessary for tracing smaller buildings or other small scale features. That is the downside of having up-to-date open data for everywhere in the world. But as said the main target here is abolishing the 15 year old even lower resolution and much poorer quality imagery. A nice secondary use is supplementing older high resolution data with information on recent changes like in case of the Vostochny Cosmodrome and the Panama Canal.

Comment from BushmanK on 20 July 2016 at 15:48

Completely support that.

Own experiments are required to learn how to get useful result, while fundamental principles of band combination are explained many times in countless sources with different level of complexity.

Nice article, by the way (and full text is available): First Experience with Sentinel-2 Data for Crop and Tree Species Classifications in Central Europe

Comment from BushmanK on 20 July 2016 at 16:21

Another good paper on band combination visualization: Displaying and Stretching 16-bit per Band Digital Imagery from USDA FSA Aerial Photography Field Office. Gives perfect illustration, why understanding is required.

Comment from Skippern on 21 July 2016 at 00:40

Could these, with bounding boxes be added to the imagery index in JOSM and other editors?

https://josm.openstreetmap.de/wiki/Maps

https://github.com/osmlab/editor-layer-index

Comment from imagico on 21 July 2016 at 08:12

@BushmanK - yes, there is a lot written about processing satellite data. Science papers are usually only of limited use though since they tend to not mention the practical problems and limitations but concentrate on presenting something as ‘nice in theory’. There is a lot of practical material available as well of course, starting with the GDAL documentation and the satellite data specifications:

http://gdal.org/gdal_utilities.html

http://gdal.org/frmt_sentinel2.html

http://landsat.usgs.gov//landsat_level_1_standard_data_products.php

https://sentinel.esa.int/web/sentinel/user-guides/sentinel-2-msi

https://lpdaac.usgs.gov/dataset_discovery/aster/aster_products_table/ast_l1t

Most practical tutorials present very specific workflows based on specific tools but can also serve as sources for general information. Like:

http://www.shadedrelief.com/landsat8/introduction.html

https://github.com/mapbox/workshops/tree/gh-pages/satellite-workshop

http://wiki.openstreetmap.org/wiki/User:Imagico/Coastline_Mapping_from_Landsat_Scenes

@Skippern - my images are in the OSM Editor Layer Index but i do not manage to keep them completely up-to-date there so you either have to enter the layers manually or wait until an update is made.

For JOSM i recommend using

http://www.imagico.de/map/osmim-imagicode.xml

in addition to the Editor Layer Index - this way you have the individual layers and an up-to-date version of the aggregate of all layers.

Comment from SomeoneElse on 22 July 2016 at 17:13

Today I updated the “FAQ” wiki page http://wiki.openstreetmap.org/w/index.php?title=FAQ&type=revision&diff=1328469&oldid=1310918 with “what imagery you could use” (just changing MapQuest to Mapbox). Perhaps it would make sense to say “… and there may be other local imagery sources available for you within your editor”?

Comment from Sanderd17 on 22 July 2016 at 19:39

This looks like great imagery for remote areas … however, most people use maps in crowded areas, and most people also map in crowded areas.

So I wonder how useful this is for OSM as a whole. In contrast to some high-res, recent and accurate imagery of a small crowded area we might get by lobbying some (local) governments.

Comment from imagico on 22 July 2016 at 20:17

I think i made it pretty clear that the primary purpose of this is to increase awareness that such imagery exists and can be used in the hope that this prevents mappers from wasting their time with 15 year old images in Bing and Mapbox. This happens to apply mostly to remote areas. The availability of up-to-date open data satellite imagery however is not limited to those areas.

Another advantage is to have up-to-date imagery for every part of the world, up-to-date here usually meaning a few weeks old, in difficult cases sometimes a few months. Age of high resolution imagery in Bing, Mapbox or from local government sources is usually at least about 2-3 years. I think i demonstrated this quite clearly with the Panama and Vostochny images.

And yes, most use of maps and most mapping takes place in crowded areas but where maps are most needed are usually the less crowded parts of the world. Or in other words - in a European or North American city a map is a luxury, in the remote parts of the world it is frequently a necessity.

Comment from BushmanK on 24 July 2016 at 17:21

@Sanderd17,

Sentinel 2 data actually can be used to update populated places too. For example, in Moscow, Russia many construction sites can only be kept up to date by using this kind of imagery. Active logging, which goes on around Moscow, also can’t be traced from archive WorldView imagery, since it’s several years old.

Speaking of lobbying, it’s it might be realistic in case of place where you live, but many countries don’t have that kind of luxury (or people, who have will and time to do that).

Login to leave a comment