[Coral-List] Fw: Aerial photos of Praslin Island, Seychelles
Klaas.Pauly at ugent.be
Thu May 31 12:02:37 EDT 2007
----- Original Message -----
From: "Klaas Pauly" <Klaas.Pauly at ugent.be>
To: <ALGAE-L at LISTSERV.HEANET.IE>
Sent: Thursday, May 31, 2007 5:45 PM
Subject: Re: [ALGAE-L] Aerial photos of Praslin Island, Seychelles
> Google Earth is a good friend when it comes to previewing a site and
> getting a general impression, or even for planning ground truthing field
> work, but it is absolutely useless when it comes to mapping - first of all
> you have no spectral information whatsoever, and more importantly, the
> coordinates are far from reliable.
> I wonder what kind of mapping study you would like to do. If you aim only
> at swimming transects with a gps and then delineating habitats on an
> aerial picture, google earth pictures might even do, as long as you
> georeference them yourself.
> However, if you would like to do satellite of airborne mapping based on
> supervised classification, there is no simple answer to your questions.
> Recent satellite or airborne imagery (on request) is always very
> expensive; airborne even more than spaceborne, but you also need to
> consider the spatial resolution you want to work at in taking a decision.
> If moderate resolutions are fine (30m), a good starting point is the free
> database of Landsat ETM imagery at
> http://glcf.umiacs.umd.edu/data/landsat/. You might want to search the FTP
> server; Praslin is located in paths 155 and 156, row 63 in the WRS-2
> system. Again, the provided georeference is unreliable, but with a bit of
> fieldwork you can directly geocode them to your own ground control points.
> You can perform an unsupervised or even supervised classification (if you
> already got recent, detailed and georeferenced ground information) on
> these images in order to see if it suits your needs. However, these
> archived images will likely be quite old.
> If you want to request new acquisitions, you might consider the
> CHRIS/PROBA sensor (18 spectral bands at about 18m resolution); if your
> project proposal gets accepted by ESA, they'll provide you imagery for
> free for scientific research. This is because the sensor is experimental,
> and although not free of flaws, the datasets have proven to be very useful
> in coastal mapping studies.
> More spatially detailed imagery (about 2m) can be obtained by IKONOS or
> QUICKBIRD, but those provide only three spectral bands. More spectral
> bands (hyperspectral datasets) on even higher spatial resolution (10s of
> cm) can be obtained by the airborne CASI sensor, but these acquisitions
> are very, very expensive.
> A methodically very good, although technically out-dated book is "Remote
> Sensing Handbook for Tropical Coastal Management", published by UNESCO.
> Decent and free (if you wait for another month) remote sensing software
> can be obtained at http://www.itc.nl/ilwis/.
> All the best,
> Klaas Pauly - Teaching Assistant, PhD student
> Phycology Research Group, Biology Department, Ghent University
> Krijgslaan 281 (S8), B-9000 Gent, Belgium
> Tel +32 9 264 8507 - Fax +32 9 264 8599
> Klaas.Pauly at UGent.be
> ----- Original Message -----
> From: "Emanuel Mendonca" <emanuel.mendonca at GMAIL.COM>
> To: <ALGAE-L at LISTSERV.HEANET.IE>
> Sent: Thursday, May 31, 2007 5:02 PM
> Subject: Re: [ALGAE-L] Aerial photos of Praslin Island, Seychelles
> Google Earth is your friend!
> 2007/5/31, Adrien Cheminee <adriencheminee at yahoo.ca>:
>> Hi everyone,
>> In order to undertake field work for marine biological monitoring at
>> Island, Seychelles, I am looking for aerial or satellite photographs of
>> north coast of Praslin. I would be very grateful for any photos or advice
>> order to gather them. I am more precisely interested in photos of the
>> near Anse Takamaka and also Anse Volbert. Field work will aim at mapping
>> main nearshore bentic habitats, more particularly seagrass beds and
>> I am consequently looking for photos with good resolution that could be
>> for preliminary photo interpretation and mapping.
>> Thanks in advance for any help,
>> Best regards,Adrien CHEMINEE
>> Adrien CHEMINÉE
>> Chargé d'étude en biologie marine
>> mel : adriencheminee at yahoo.ca
>> adresse : 10 rue Pastoret 13006 Marseille, France
>> tel: (+33) 6 81 73 95 19
>> Obtenez des réponses à vos questions ! Profitez des connaissances et des
>> opinions des internautes sur Yahoo! Questions/Réponses.
> The Mediterranean - a gateway, not a barrier,
> The Wind - a driving force, not a obstacle,
> The Nature - a mother, not an enemy.
More information about the Coral-List