Hello,

I've just started using SEPAL to look at some satellite images over time of forest areas in the Sahel. So far the resolution on the resulting files is very coarse and I wondered if anyone knew how to improve this? The file sizes are around 2MB and I would like them to be more like 200MB if poss.

Thanks!

Sam

asked 20 Dec '18, 10:52

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SPearce
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Hi Sam, Thanks for your question, even though it is formulated strangely. Could you be more precise about which images you are looking at? Are you creating mosaics ? There are a lot of functionalities in SEPAL and it is difficult to solve your issue without more details Please explain better Thanks Remi

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answered 20 Dec '18, 17:03

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lecrabe ♦
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Hi Remi,

Good to hear from you. Sorry if my question was unclear - I'm fairly new to this topic. I'm trying to look at small areas of community forest in Burkina Faso, and try to see if there is any difference in tree cover over time. So far I've been creating mosaics to do this.

I have been advised to use data from Sentinel rather than Landsat, as this will give me higher res images. However, when I have downloaded the sentinel images from SEPAL they come out very coarse, and not useable for analyses of small areas.

Can you help with this? Is there a setting on SEPAL where I can increase the resolution of the images?

Thanks,

Sam

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answered 20 Dec '18, 17:32

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SPearce
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Hi Sam,

Thanks for the clarification.

Sentinel 2 is at 10 m spatial resolution for the visible and NIR bands, and this is what you will get, you can't increase the resolution of the satellite imagery itself. Landsat is ~30m, so the level of details you can catch with Sentinel 2 is indeed higher (you can see objects 9 times smaller). But both levels of resolution are quite adapted for tree cover mapping and forest change detection when you want to process and analyze data automatically and there is a lot of literature on that subject. Those sources of data are free and public and this also explains why they are so widely used. Higher resolution imagery is available for earth observation but not for free, at that stage.

In any case, from your message I understand you want to analyze the change visually rather than through a machine learning process and in this case you could look at other tools provided in the OpenForis suite.

In particular, Collect Earth is a free and open-source image viewing and interpretation tool, suitable for projects requiring information about land cover and/or land use, where users can analyze high and very high resolution satellite imagery.

You could use the newly launched online tool (still under development, available here: collect.earth) or the desktop version (fully operational, available here: http://www.openforis.org/tools/collect-earth.html).

Hope it helps. Remi

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answered 21 Dec '18, 09:36

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lecrabe ♦
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question asked: 20 Dec '18, 10:52

question was seen: 255 times

last updated: 21 Dec '18, 09:36