No shoreline

[ReggieRocket]

Hi Yarran,

This such a great tool! I'm excited to measure the accuracy of shorelines compared to CoastSat.

Something interesting is happening with my dataset. Shorelines are only being drawn on about 1/4 of all the good quality images. I attached an example of this. Something I'm noticing is that there isn't many sand pixels in the classified image of the whole dataset. Do you think that's causing it?

Let me know what other information would be helpful!

Thanks, Shannon

[ReggieRocket]

This was happening at another site as well. That site has less images and a much quicker processing time, so I retrained the classifier and it is doing well picking out the different classes, but still there is no shoreline.

[ydoherty]

Hi Shannon,

Apologies for the delay, I’ve had a busy week at work and upkeep this git in my free time now. For the first email I would say re-training the classifier would be the first thing to check. Seems like you’ve done that for the second email however .

Other setting to check would be:

• have you drawn the reference shoreline close enough to the expected shoreline location? And if so is the max_dist_ref buffer distance from the ref shoreline enough? The default of 75m should work in almost all cases though

• from you images, it looks like you’re downloading a small section of beach. The min_beach_area (in m2) setting may be impacting the shoreline drawing. If the number of pixels classified as sand is less than this area, it won’t draw a shoreline. This is for sites where there may be back beach dunes you don’t want to contour. Try dropping this number significantly and seeing if it works (maybe start with 100 then work up if it works)

• Similar to the above, if you’ve only got a small image, you’ll also need to drop the min_length_shoreline down from the default 500m. All contours less than this length are dropped. Again try dropping this significantly then work up from there if it’s works (starts around 50m maybe)

If those don’t work there are some further settings you could play around with in the …coastsat_ps/data_import.py file. Although these settings should be a last resort as they change how bits of code run.

Let me know if those work!

Cheers, Yarran

On Tue, 14 Feb 2023 at 02:00, ReggieRocket @.***> wrote:

This was happening at another site as well. That site has less images and a much quicker processing time, so I retrained the classifier and it is doing well picking out the different classes, but still there is no shoreline. [image: 2018-11-18 17_46_24 2018 PS2 shoreline plot] https://user-images.githubusercontent.com/21685436/218491144-de6ad5f4-e018-44a6-9e53-ec50089f9d5e.png

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