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Topic: rapideye as aerial photo

I am working with seismic terrain dispplacements in SE Spain. I have a collection of data: aerial photo, and SPOT imagery plus dems of 5m covering the area. One of the Spot images is just 20 days before the quakes.. but I do not have post-imagery with the exception of a Rapideye image just one day after the quakes. I am thinking of using this image as an aerial Photo once corrected... I know that Rapideye is a pushbroom tool, but what more can I do?. Is it possible to write a pseudo ancillary file using the metadata of the Rapideye?

Excuse me for this heretical behaviour.

C. Boldo

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Re: rapideye as aerial photo

Hi, what is the magnitude of the earthquake?

SPOT data at 2.5m with 5m DEM will allow you to study an earthquake that produced more than 50cm of sharp ground rupture. For that, you certainly need a magnitude greater than 6.8 and I don't think any recent earthquake produced such displacement recently.

Using RapidEye, given the intrinsic quality of the data, I don't think you would be able to measure seismic rupture from an earthquake of magnitude less than 7.0.

Sebastien

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Re: rapideye as aerial photo

Hi Sebastien, this is my second answer to your post. It seems that the previous one has not been registerred. As matter of fact it was a serie of seismic events during 6 days with a final one of magnitude 5. All of them along a well know  strike -slip fault . They caused severe damage ay buildings and loss of human lives. The fault was controlled by a network of fixed GPS stations, but the closest to the epicenters was damaged. I have a SPOT 5 images 20 days before the quake, and I am striving to get a second SPOT 5 registered just one day after the last shock. The  dem is a good one based on lidar and I have another old SPOT 5 orthorectified with the dem and some old digital aerial pictures  woth the same orthorectification. The main problem is that the first image that I have is the rapideye taken the same day than the second SPOT. Meantime I am asking to have the original LAS Lidar data and post aerial photo, but  it takes time and a lot of paper-
I will report what I can do with this mess...

Thanks again

Carlos

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Re: rapideye as aerial photo

Hi Carlos,

If you have pre and post earthquake Lidar, you could certainly correlate the gridded Lidar data. We've proved the concept  for the USGS on the El-Mayor earthquake in 2010, and we've been applying the technique for more commercial applications:
http://www.imaginlabs.com/#!state/news/christchurch

Why would you need the Rapideye image since you have the SPOT image before the earthquake? Just try to the get one SPOT before and one SPOT after, and you're done. Why bother with RapidEye, which offers lower resolution?
I hope you have access to the SPOT 1A level images, not some ortho-ready format full of topo errors.

I'm just trying to understand the story so I can best advise.

Thanks,
Sebastien

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Re: rapideye as aerial photo

Hi Sebastien,
I am affraid that Lidar data will be pretty old and pre-earthquake. Main problem here is that I am dealing with town, provincial, authonomical, statal and international offices and each of them provide data in their own time and manner. Mostly treated in one of their wise procedures. (all of them differents). In other words a pain in the ... Rapideye was the first one in deliver original data with ancillary info. By the time being I have original SPOT -5 L1A level with dimap file for the pre-image, plus an orthorectyfied version,plus ortho mosaics of the same area. All of them ,excepting Rapideye, pre -earthquale, that is why I was thinking in making a try while waiting for the rest of the data. I do believe that ISIS will provide the post earthquake original SPOT-5 in some weeks. and that will be more ortodox.

Meanwhile, I will ortho rectify the original pre image using the 5m dem, and the other two sources and have a look to check which source wil be the best.
Thanks for your attention and good will. I will be making a trip for a week, But I will keep in touch.

Carlos

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Re: rapideye as aerial photo

Hi Carlos,

I understand better, tks for the explanation. My advise is to start with the easiest solution before going into more complicated experiments. Hence:
- Start by producing the pre-earthquake SPOT5 image. Make sure your DEM covers the whole image. If not, you'll have to take GCP only in the area the lidar is valid and you should only ortho-rectify the image on a subset where the LiDAR exists. Otherwise, COSI-Corr will give fancy results that will propagate in the image (it's a limitation of our code).
- I'm anticipating the SPOT ortho-ready to be quite useless for your work.
- Given that RapidEye has lower resolution that SPOT5 and that dates are about the same, I don't see RapidEye adding any sort of information.

- The best case scenario would be that the LiDAR covers all, or most of the SPOT scene. Then, create a shaded DEM based on the illumination of the SPOT scene (we give you those when you build the SPOT ancillary data in COSI-Corr), and then optimize GCPs between the raw SPOT and the shaded DEM liDAR. Then orthorectify the SPOT image.

- Make sure your LiDAR is in UTM coordinates on a square grid (5x5m), it'll make your life easier.

- You were mentioning aerial photographs. You could certainly use those as well, but the 5m LiDAR won't be sufficient for that purpose. Aerial photos usually have quite high resolution and larger incidence angles. They're hence more sensitive to topography. For aerial photographs, I would suggest using an external software like ERDAS LPS to determine a bundle orientation with DEM creation, then create a rigorous ortho-moasic. COSI-Corr could be used to correlate ortho-mosaics.

Sebastien

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Re: rapideye as aerial photo

Hi Sebastien, Part of my trip is on the following of the Lidar, tks  for your advice, I was looking for a small part of the SPOT imagebut now I am learned to go for the full scene. I will keep in contact .

Best regards
Carlos

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Re: rapideye as aerial photo

Hi Sebastien,
Las data will be available but.. delayed. I am waiting for the long wished SPOT 2.5 covering the area (three days after the quakes), wich will be supplied by ISIS (God bless them!). But I am afraid that I will be busy in other affairs until the end of the next summer, such is actual times. If I can try something  I will report, but do not expect more entrances in the next 2-3 months.

Best regards
Carlos

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Re: rapideye as aerial photo

Sure, good luck with your other projects as well,

Best,
Sebastien

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Re: rapideye as aerial photo

Hi Sebastien,
Here am I again. There were changes in my absence, some of them good. I got a second SPOt post earth-quake and very fresh and a good set of lidar las files. I tiled the "las" to a mosiac of 1m pixel size and I will check this behave. Bad luck is that it does not cover the full space of the SPOT images but it fits quite correctly over the quake zone and the main fault. I will see how it behave....

Best regards
Carlos