Landsat and GM issues Part 1

Chris_Chris_ Global Mapper UserPosts: 31Trusted User
edited February 2012 in Raster Data
LANDSAT IMAGERY

I need help with Landsat imagery:
- technical
- sources.

GM offers 2 sources:
- WMS Global Mosaic, pan sharpened
Post 01a.jpg
- WMS Global Mosaic, not pan sharpened
Post 01b.jpg
It is not possible to download the individual elements -- as far as I can tell.
I would like access to each of the Landsat ETM+ bands separately.
Post 01c.jpg
These do not allow access to individual bands.

Natural Pan-sharpened:

-- shows this…
Band 4 is identified with Red; as well as Band 1.

As I understand it -- please correct me and / or clarify -- that:
Band 1 -- Blue-Green
Band 2 -- Green
Band 3 -- Red
Band 4 -- Near-Infra-red (NIR)
Band 5 -- Mid-IR (MIR)
Band 6a -- Thermal-IR (low) (TIR)
Band 6b -- Thermal-IR (high) (TIR)
Band 7 -- Mid-IR (MIR)
Band 8 -- Panchromatic.
All are different wave lengths.

I’m sure that GM should present the Bands as Blue, Green, Red; not Red, Green, Blue. This may simply be a mix up with colour notation -- RGB. For Landsat natural images this would be BGR -- confusing.

Natural 321 that is pan sharpened becomes 321+8.

Again, as I understand it, it is Band 8 (monochromatic 15m res.) that makes the lower resolution imagery sharper.

Please confirm or correct me on this -- I’m no expert.

False colours are usually presented as:
-- 432 (432+8 PS) false colour
-- 742 (742+8 PS) SWIR (GeoCover).
[Sources: Spatial Mapping website, Ed Johnson’s Blog, USGS Rocky Mountain Mapping Center]
I downloaded some Landsat 7ETM+ natural PS to test…
Post 01d.jpg
…and exported as 4-band -- selecting No here.

Post 01e.jpg
On the left -- how GM normally presents the RGB Bands.
All the information I have read suggests this should be presented as on the right.(See next Post)

Could someone please comment.

Comments

  • Chris_Chris_ Global Mapper User Posts: 31Trusted User
    edited June 2011
    [Necessary to include all images]
    LANDSAT IMAGERY: PART 2
    Post 01f.jpg
    All the information I have read suggests this should be presented as on the right.

    Post 01g.jpg
    When dropping the menu, 4 bands show, but Band 4 is not really usable -- that I know of -- because it need NIR.
    Post 01h.jpg
    This is where I get totally lost…
    -- should GM have an 8 Band menu instead of RGB???
    -- how can I select Band-4 to get NIR? -- or any other band beyond 3.
    -- if RGB channels are correct, should there be an additional grey / monochrome channel?

    I tried the experiment again, creating 8 bands…

    There was no difference between 342 and 742.
    I assume there is no NIR or panchromatic in these data sources -- is this correct?

    What is needed is the full set of 8 band data for download in individual bands.

    Another experiment…
    I loaded 3 separate Landsat 7 files downloaded from Global Land Cover (http://glcf.umiacs.umd.edu/) corresponding to Bands 7, 4 and 2. Band-2 show below and hides the others.
    Post 01i.jpg
    Try as I may, I cannot get these, or any other combination, of such images to produce colour. The only colouration I get is through some of the blends.

    Put these into GIMP and I get proper colour images?

    What’s happening?

    What’s lacking?

    Just to prove the 3 grey images make a coloured image…
    Post 01j.jpg
    …using GIMP.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2011
    The WMS Landsat sources don't provide the full collection of bands, they have already created a 24-bit color JPG image as RGB with the bands combined as described. You can't really do any useful band manipulation on the WMS sources as they have been stripped of the full set of bands.

    You can use the method described at http://globalmapper.com/support/faq.htm#22 to combine imagery where each band is in separate file into a color image.

    See http://landsat.usgs.gov/Landsat_Search_and_Download.php for more information about the Landsat bands (depending on the sensor) and to download some Landsat imagery.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Chris_Chris_ Global Mapper User Posts: 31Trusted User
    edited June 2011
    Thanks Mike -- I'll come back to your response in a minute.

    First, the results of a disturbed nights sleep...
    Go back to the previous image with the greyscale L7. You'll see I highlighted all 3 layers (files, bands) and worked on them together. I now realise this was a mistake. So, I worked on each of the layers seperately. Further experimentation resulted in successful colourisation, but dark -- just as Mike said in his reply. Darkness and quality were poor, so I added another file / layer -- Band 8 image.

    NOTE: All the following images are 20% of original and therefore suffer in quality for uploading.

    GLOBAL MAPPER tests with Landsat 7 ETM+
    VD GLCF test 2.gmw 321+8
    Layers (Source: Global Land Cover):
    L72169028_02820060620_B80.TIF.gz = Band 8 (panchromatic) greyscale; 15m resolution
    L71169028_02820060620_B10.TIF.gz = Band 1 (Blue); 30m resolution
    L71169028_02820060620_B20.TIF.gz = Band 2 (Green); 30m resolution
    L71169028_02820060620_B30.TIF.gz = Band 3 (Red); 30m resolution
    Overlay Control Centre: Options -- settings used:
    All Bands -- Bicubic Interpolation
    Band 8 -- Blend = Darken; Contrast = Percentage Stretch (value = 1)
    Band 1 -- Blend = Multiple; Contrast = Percentage Stretch (value = 0.4); Colour Grade = Red and Green output range 0.
    Band 2 -- Blend = Keep Green; Contrast = Percentage Stretch (value = 0.4); Colour Grade = Red and Blue output range 0.
    Band 3 -- Blend = Screen; Contrast = Percentage Stretch (value = 0.4); Colour Grade = Green and Blue output range 0.
    VD SW test 4-band 02 resize 20%small.jpg
    This is the nearest I got to natural image with acceptable quality (eg clarity). I'm not sure I would consider this a success at obtaining a natural image, but it is reasonable for detail.
    Hopefully, the detail listed above are self-explanatory.

    VD GLCF test 3.gmw 321+8
    Layers (Source: Global Land Cover):
    As test 2
    Overlay Control Centre: Options -- settings used:
    All Bands -- Bicubic Interpolation
    Band 8 -- Blend = No Bland; No Contrast.
    Band 1 -- Blend = Keep Blue; Contrast = Percentage Stretch (value = 0.4).
    Band 2 -- Blend = Keep Green; No Contrast.
    Band 3 -- Blend = Keep Red; Contrast = Percentage Stretch (value = 0.4).
    VD SW test 4-band 03 resize 20%small.jpg
    Next step in improving the clarity -- better, but further from natural.

    VD GLCF test 4.gmw 321+8
    Layers (Source: Global Land Cover):
    As test 2
    Overlay Control Centre: Options -- settings used:
    All Bands -- Bicubic Interpolation
    Band 8 -- Blend = No Blend; No Contrast.
    Band 1 -- Blend = Keep Blue; Contrast = Percentage Stretch (value = 0.6).
    Band 2 -- Blend = Keep Green; Contrast = Percentage Stretch (value = 0.6).
    Band 3 -- Blend = Keep Red; Contrast = Percentage Stretch (value = 0.6).
    VD SW test 4-band 04 resize 20%small.jpg
    Last of the 321+8 images. The best clarity, but more like false colour.

    VD GLCF test 5.gmw 742+8
    Layers (Source: Global Land Cover):
    L72169028_02820060620_B80.TIF.gz = Band 8 (panchromatic) greyscale; 15m resolution
    L71169028_02820060620_B20.TIF.gz = Band 2 (Blue); 30m resolution
    L71169028_02820060620_B40.TIF.gz = Band 4 (NIR); 30m resolution
    L71169028_02820060620_B70.TIF.gz = Band 7 (MIR); 30m resolution
    Overlay Control Centre: Options -- settings used:
    All Bands -- Bicubic Interpolation
    Band 8 -- Blend = No Blend; No Contrast.
    Band 2 -- Blend = Keep Blue; Contrast = Percentage Stretch (value = 0.5).
    Band 4 -- Blend = Keep Green; Contrast = Percentage Stretch (value = 1.5).
    Band 7 -- Blend = Keep Red; Contrast = Min / Max Stretch.
    VD SW test 4-band 05 resize 20%small.jpg
    False colour attempt, or more precisely SWIR (GeoCover) colour attempt. Honestly, no different from 04 -- natural meets false.

    Images references:
    1 - 5.

    Response on source of banding images:
    Only place I found them was at Global Land Cover Facility. Hence my inclusion of the full file names to show they are supposed to cover all bands (ie last 3 digits -- eg B70 = Band 7).

    If anyone can offer me better settings to get sharp natural and false colour images; I would be most greatfull.

    Also, if anyone can offer a method for isolating water to create a 2 colour image that I can vectorise to extract the water as a seperate file -- that would also be appreciated.

    Chris
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2011
    Chris,

    I would suggest using bands 3, 2, 1 with the Keep Red, Keep Green, and Keep Blue blend modes and maybe try a min-max contrast adjustment. Load the higher detail panchromatic layer on top of that and set its blend mode to Apply Color. That will apply the colors from the other bands to the higher detail of the panchromatic layer. As you have it now with your panchromatic layer underneath the others it really isn't even visible.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Chris_Chris_ Global Mapper User Posts: 31Trusted User
    edited June 2011
    Many thanks for that Mike -- much appreciated.
    Chris
  • Chris_Chris_ Global Mapper User Posts: 31Trusted User
    edited June 2011
    Just thought people would like to see the difference placing Band 8 on top makes to the clarity and detail of the image. It also helps with the colour.
    It's a great difference -- thanks again Mike.

    The order of the images is the same as posted earlier.

    VD SW test 4-band 02a resize 20%.jpg

    VD SW test 4-band 03a resize 20%.jpg

    VD SW test 4-band 04a resize 20%.jpg

    VD SW test 4-band 05a resize 20%.jpg

    Just in case anyone is interested -- these images are of the south western part of the Volga Delta.

    Chris
  • richardhcrichardhc Global Mapper User Posts: 4
    edited November 2011
    This has been a very interesting and useful thread. Thanks. I was faced with the same questions way back in version 7 - I never did get a satisfactory natural color (like the i-qubed landsat colors) with Global Mapper by itself but did get an acceptable image and then tweeked it in Photoshop. To get a good result I had to mask the coast-line then adjust the colors in the ocean separately from the land colors. I'd be interested in anyone else's settings for GM that resulted in really nice colors.
  • Chris_Chris_ Global Mapper User Posts: 31Trusted User
    edited November 2011
    richardhc wrote: »
    This has been a very interesting and useful thread. Thanks. I was faced with the same questions way back in version 7 - I never did get a satisfactory natural color (like the i-qubed landsat colors) with Global Mapper by itself but did get an acceptable image and then tweeked it in Photoshop. To get a good result I had to mask the coast-line then adjust the colors in the ocean separately from the land colors. I'd be interested in anyone else's settings for GM that resulted in really nice colors.
    Many thanks for your post -- much appreciated.
    I was just learning with help from Mike and others; so I am unfamiliar with soem of the terms you use...
    ...i-qubed...

    I used GIMP, Paint.Net and PaintShopPro to get results, but the 8 bands produce the best results for getting the most detail.

    I don't think I know how to create the sought of mask you talk about -- did you mean in GM or Photoshop?
    I tried masking in GIMP, but didn't get on with it to well.

    Again, your response most appreciated -- glad it was of use / help.
  • ChuckBChuckB Global Mapper User Posts: 30Trusted User
    edited February 2012
    richardhc wrote: »
    This has been a very interesting and useful thread. Thanks. I was faced with the same questions way back in version 7 - I never did get a satisfactory natural color (like the i-qubed landsat colors) with Global Mapper by itself but did get an acceptable image and then tweeked it in Photoshop. To get a good result I had to mask the coast-line then adjust the colors in the ocean separately from the land colors. I'd be interested in anyone else's settings for GM that resulted in really nice colors.

    Yes, an interesting and useful thread!

    Settings ...

    Band 1: Keep Blue; Linear Stretch, 1 std. dev.; Lower end of input range for Color Grade at 75
    Band 2: Keep Green; The rest the same as Band 1
    Band 3: Keep Red; The rest the same as Band 1
    Band 4: Keep Green; Linear Stretch, 2 std. dev.; Translucency at 23.2 percent: (Just to boost green a bit)
    Band 8: Overlay (not Apply Color)

    URL to data: ftp://ftp.glcf.umd.edu/glcf/Landsat/WRS2/p169/r028/L71169028_02820060620.ETM-GLS2005/

    GM workspace file: Volga river delta.gmw

    Full tile
    Volga river delta - full scene.jpg

    Zoomed in
    Volga river delta - zoom.jpg

    Zoom to "full detail"
    Volga river delta - detail.jpg
  • Chris_Chris_ Global Mapper User Posts: 31Trusted User
    edited February 2012
    I'm really glad you found it useful - thanks.
    Haven't used GM in quite awhile - tied up with other things, but I'll come back to your files at some point in the future.
    Thanks
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