Query Regarding Shoreline Analysis and Image Extraction Compatibility with SAET

[Qikewen69]

Dear developer,

I would like to analyze shorelines along my Area of Interest (AOI) spanning the past 20 years. However, I have observed that I am unable to acquire satellite images predating the launch of Sentinel-2 and Landsat. Consequently, I need to obtain satellite images from alternative sources for the period 10 years ago. Could you please confirm whether this SAET allows users to extract shorelines from images obtained from sources other than Sentinel-2 and Landsat?

[jpalomav]

Hi. SAET was designed originally to help the impact anslysis for coastal storms. So, at this moment, SAET is able to deal with Landsat 8, 9 and Sentinel-2. That means that you can analyze images Landsat 8 since 2013, Landsat 9 since 2022 and Sentinel-2 since 2015. Other older satélites like Landsat 7 (1999) or Landsat 5 (1984) are not available in SAET at this moment, but we are thinking of include them in order to facilitate time series analysis. Best regards, SAET team El mié, 20 dic 2023, 4:38, Qikewen69 ***@***.***> escribió:

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Dear developer, I would like to analyze shorelines along my Area of Interest (AOI) spanning the past 20 years. However, I have observed that I am unable to acquire satellite images predating the launch of Sentinel-2 and Landsat. Consequently, I need to obtain satellite images from alternative sources for the period 10 years ago. Could you please confirm whether this SAET allows users to extract shorelines from images obtained from sources other than Sentinel-2 and Landsat? image.png (view on web) <https://github.com/jpalomav/SAET_master/assets/154396997/ecc8bce2-641a-41c8-a1b6-7c97137c30d6> — Reply to this email directly, view it on GitHub <#2>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AXW6C6VEHDKZM34EQ2P6OODYKJMSRAVCNFSM6AAAAABA4FGJ5KVHI2DSMVQWIX3LMV43ASLTON2WKOZSGA2DSNZXGQ4DAMQ> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[Qikewen69]

Thank you for your prompt response and clarification regarding the satellite sources currently supported by SAET. I appreciate the detailed information provided.

I noticed that Landsat 7 images, despite not being officially supported, seem to work when downloaded and placed in the "data" folder. The SAET successfully generated shorelines from these older Landsat 7 images. Can you confirm if SAET is indeed compatible with Landsat 7? If so, are there any specific considerations or limitations I should be aware of?

Thanks for your assistance.

[jpalomav]

Hi.
Thanks for your interest. In this case , if SAET has been able to extract the shoreline, probably the result is not correct (or not so correct as we will expect). SAET works with water indexes (AWEInsh, AWEish and MNDWI). These indexes combine some bands to emphasize the difference between water and non water surface. Mayority of these water indexes use Green, blue, NIR, SWIR1 and SWIR2 bands. The problem is that there is no correspondence for these bands in all satellites. For example, SWIR1 (short-infrared) band for Landsat 8-9 is the band B6 but for Landsat 7 and 5, this is the band B5. So , the mathematical equation for one water index is taken onto account different bands for L8-9 and L5-7, and the water index result wont't be correct. If you dive into the script "sp_processing_functios.py", in the line 2484 there is a function called "aweinshLandsat" where you can see the expression to compute the AWEInsh water index. For L8-9 the suitable bands are: green(B3), nir(B5), SWIR1(B6) and SWIR2(B7). For L5-7 this expression should be: green(B2), nir(B4), SWIR1(B5) and SWIR2(B7).

Other point is that L7 satellite had a problem on 2011 and from this year L7 images present a "gap" effect (SLC-off data). So these images must be processed taken this fact into account.

We know the importance to be able to analyze coastal sectors from ahistorical point of view and take advantage of all image resources. So we are thinkig of include L5 and L7 in the SAET workflow, but it won't be inmediatly, may be in the next months.

In any case, we will announce it through this website.

Best regards,

SAET team.

[Qikewen69]

Thank you for the clarification. I appreciate your efforts and look forward to potential updates. Your commitment to enhancing SAET is commendable.