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GIS/ValTech 2021 has ended
NOTE THAT THIS IS NOT THE CONFERENCE PLATFORM AND YOU CAN NOT ACCESS THE VIRTUAL CONFERENCE THROUGH THIS AGENDA/APP. If you registered for the conference, you were sent an email on Friday, March 19 with instructions to access the conference platform. If you cannot locate that email, please check your junk folder first and then send an email to vmcbride@urisa.org to verify your registration.

Welcome to the 24th Annual GIS/Valuation Technologies Conference, co-hosted by the International Association of Assessing Officers (IAAO) and the Urban and Regional Information Systems Association (URISA). The conference will be presented virtually this year during the week of March 22-26, 2021. The workshops and sessions are detailed here. Note that the schedule appears in the Central Time Zone.

Join IAAO and/or URISA and qualify immediately for the discounted Member Conference Rates. Young professional and student registration fees are further discounted.

REGISTRATION: The cost to participate – for attendees and our partners – has been significantly reduced (by 50% or more) in order to make it easier to attend. You must register to access the online conference. All registered attendees will receive emailed instructions before the conference begins on March 22. Review registration details here.

With work, school, and family commitments, you may not be able to attend every session as it occurs ’live’. No worries! After the conference, registered participants will be able to view the presentation recordings whenever it is convenient.

NOTE THAT THIS IS NOT THE CONFERENCE PLATFORM AND YOU CAN NOT ACCESS THE VIRTUAL CONFERENCE THROUGH THIS AGENDA/APP. If you registered for the conference, you were sent an email on Friday, March 19 with instructions to access the conference platform. If you cannot locate that email, please check your junk folder first and then send an email to vmcbride@urisa.org to verify your registration. 
Back To Schedule
Wednesday, March 24 • 10:45am - 11:45am
Shadow Detection and Correction Using 3D GIS and Image Processing

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Shadow has always been an issue for a plethora of image processing applications. Since, its presence deteriorate the visual quality of the image, which results in a loss in information that can be drawn from it.
Thus, this work presents an effort to contribute a new solution for an old challenge, an automatic method for cast shadow detection and compensation from orthophotos using a conjunction between 3D GIS and image processing. In a first phase, the outline of the developed process involves a new workflow that aims to use 3D GIS technology to detect cast shadow appearing on orthophotos. This new workflow was divided into four sub-steps. First, we needed to extract building footprints from LIDAR data. Then, we used 3D GIS technology to generate building multipatch and to calculate the shadow volumes that we used afterwards to create a shadow mask that points out the shadow regions existing on the orthophoto.

In a second phase, we used an image-processing algorithm that aims to compensate the shadowed regions. We applied it on the whole image including its already non-shadowed regions. Then, we integrated the already determined shadow mask to replace the shadowed regions with their equivalent after compensation. To obtain at last, the desired outcome which is a de-shadowed orthophoto.

To evaluate the performance of the proposed methodology, evaluation metrics involved in shadow detection and compensation techniques were also reviewed. In short, in this project, we focused on delivering a new approach that combines 3D GIS for the cast shadow detection and image processing algorithms for shadow compensation.


Speaker: Safa Ridene, GIS Engineer, Kelibia, Nabeul - Tunisia

Moderators
avatar for Alex Hepp

Alex Hepp

Director Assessment, Cyclomedia Technology, Inc.

Speakers
avatar for Safa Ridene

Safa Ridene

GIS Engineer, ST2i
Safa Ridene is an avid GIS Engineer. Graduated with honors from School of Geomatics and land surveying engineering, IAV Hassan II (Morocco). Safa has done her graduation internship in France. After which, she had her first paper published in the International Journal of Geomatics... Read More →


Wednesday March 24, 2021 10:45am - 11:45am CDT
Virtual