Different ways lead to different results? Experiences on modern photogrammetric surveying on...

Angela MANCUSO - Andrea PASQUALIDIFFERENT WAYS LEAD TO DIFFERENT RESULTS?EXPERIENCES ON MODERN PHOTOGRAMMETRIC SURVEYINGOF CULTURAL HERITAGE SUBJECTS

DIFFERENT WAYS LEADTO DIFFERENT RESULTS?

Experiences onmodern photogrammetric surveying

of cultural heritage subjects


October 2011, University of WashingtonBuilding Rome in a Day

“Entering the search term Rome on Flickr returns more than two million photographs. This collection represents an increasingly complete photographic record of the city, capturing every popular site,

facade, interior, fountain, sculpture, painting, cafe, and so forth. It also offers us an unprecedented opportunity to richly capture, explore

and study the three dimensional shape of the city.”

(text and images from: http://grail.cs.washington.edu/rome/)


What about quality of the models?

From the american experience, we want to try if the resulting quality of the models could be enough high to be useful for study and research.

The final quality depends, almost entirely, on the quality of the photos founded in the web: you can’t influence the lighting, pixels, focus point, total

coverage of the subject (and many other parameters), of someone’s else tourist’s photos.


Searching a good subject:a statue in Florence.

We try to search a statue in Florence, our city, that could be: - very popular among tourist,- accessible at any time of the day;

that could have: - interesting shape,- historical value,- accessible from 360°,- correct dimension related to a man with a tripod and no other instruments.

(image from: http://www.freevax.it/TOSCANA/Firenze01/LoggiaDeiLanzi.htm/)

1,65mt

3,19 mt


Choosing between:

“Fontana del Bacchino” Boboli Gardens, Florence

(image from: http://it.wikipedia.org/wiki/Fontana_del_Bacchino_(Boboli)/)

“Fontana del Porcellino” Hall of the New Market, Florence

(image from: http://static.panoramio.com/photos/large/56165146.jpg/)


The “Fontana del Porcellino”Hall of the New Market, Florence.

Has been our choose because: - very popular among turist,- accessible at any time of the day,- interesting shape,- historical value,- correct dimension related to a man with a tripod and no other instruments.

Instead the “Fontana del Bacchino”, was not so useful because:- of its location inside the Boboli Gardens, we can’t visit during early morning hours;- of its position really near to the wall behind, so we can’t do a right survey campaign of the back and neither tourist can’t!


The “Fontana del Porcellino” - Hall of the New MarketHistorical notes

- This fountain is one of the most popular monuments of Florence;

- The statue was sculpted by Baroque master Pietro Tacca (1577–1640), the best student of Giambologna in 1634;

- The model comes from a Roman copy of an Ellenistic marble that Pope Pio IV gave to Cosimo I de Medici during a meeting in Rome in 1560;

- In 1640 the statue was converted into a fountain;

- The base is octagonal, with a small pool where falls the stream of water from the mouth of the boar and is decorated with a representation of the swamps, reptiles and clams that are the environment of the wild boar.


Processing

Our process is based upon two different survey campaigns:

- DIRECT SURVEY CAMPAIGN (DSC)The DSC is executed in situ, in a short time, by a single operator with a tripod, so the resulting images are uniform for coloring and lighting.

- WEB ARCHIVE SURVEY CAMPAIGN (WASC)The WASC is a selection of web images cha-racterized by many differences: various photo-graphic equipments, light conditions, exposure, web compression alterations, but also many points of view.


Processing: the DSC survey campaign

-First Phase-

What we need...- REFLEX digital camera;- TRIPOD.

What we need to do...- Photographic survey campaign executed with a Nikon D700fx plus a Sigma 12-24mm lens and a Nikon D7000dx plus a Nikkor 16-85mm, for a total of 288 photos.



-Second Phase-

What we need...- COMPUTER;- Photogrammetry SOFTWARE.

What we need to do...- Allign photos to build the SPARSE POINTCLOUD.



-Third Phase-


What we need to do...- Build the DENSE POINTCLOUD.



-Fourth Phase-


What we need to do...- Build the MESH on the Sparse Pointcloud.



-Fifth Phase-


What we need to do...- Build the TEXTURE.


Processing: the WASC survey campaign

-First Phase-

What we need...- COMPUTER;- WEB connection.

What we need to do...- Search and choose photos from the WEB (without copyright), for a total of 116 shots.



-Second Phase-


What we need to do...- Allign photos to build the SPARSE POINTCLOUD.



-Third Phase-


What we need to do...- Allign photos to build the DENSE POINTCLOUD.



-Fourth Phase-


What we need to do...- Build the MESH on the Sparse Pointcloud.



-Fifth Phase-


What we need to do...- Build the TEXTURE.


Metrical comparison on the meshes:Raindrop Geomagic Qualify

We used two different scales of comparison:

- A: high tolerance;

- B: low tolerance.


A: high tolerance


B: low tolerance


A: high tolerance


B: low tolerance


RESULTS DIAGRAMS

A: high tolerance B: low tolerance


What about our RESULTS?

The three-dimensional model obtained from the DSC is practicaly perfect and ready to be used in something like studies or web development:

- POINTCLOUD, sparse and dense,- MESH,- TEXTURE,

all have good definition.


What about our RESULTS?

The three-dimensional model obtained from the WASC is not as acceptable and it is not suited to scientific aims:

- POINTCLOUD, sparse and dense,- MESH,- TEXTURE,

are not able to describe the complete geometry of the subject.


DSC WASC


Thank you for you attention,have a nice CHNT19!

Different ways lead to different results? Experiences on modern photogrammetric surveying on...

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