HOUSTON, TEXAS

Stuart Roberts, HDS Dept.

Digital Photogrammetry

Digital Photogrammetry

Digital Photogrammetry

State-of-the-art photogrammetric software systems, use

of consumer digital camera technology and computer

vision techniques, offer an attractive high accuracy

solution when laser scanning is not a option.

Repeatability and image stability has been paramount to

the art of photogrammetry.

Digital Photogrammetry

Three main categories can be distinguished from single photograph, stereo and convergent.

Reference: GRUSSENMEYER, P., HANKE, K ., STREILEIN, A.

Architectural photogrammetry.

Different methods can be used.

Three main categories can be distinguished from single photograph, stereo and convergent.

Reference: GRUSSENMEYER, P., HANKE, K ., STREILEIN, A.

Architectural photogrammetry.

Average project is about 13 to 20 photos. Field collection takes about one hour to place targets, photograph, and 1 hour to analyze the photos. Larger projects of up to 100+ photos can be performed.

Analyze photos?

In photogrammetry, there is a hard 3X3 rule. The photography has to be taken in a manner to place a reference mark on the same spot in three different but convergent photographs. The next example is an actual project.

DIRECT MEASUREMENTS

How quickly can I get my information?

Depending on the complexity of the job and the number of photos, relatively quickly. 9 photos can be ready in about an hour. After a QC check, 3D point data can be extracted and exported.

How accurate is the data?

Overall, photogrammetry is equal or exceeds scanning

depending on clarity and pixel count.

An off the shelf consumer camera can generate data in the

sub-millimeter range.

What is the cost?

The cost is generally 50% to 75% lower than scanning.

Major savings can be attained by not having to ship heavy

equipment associated with scanning. Field time is greatly

reduced.

When is it feasible to perform photogrammetry?

Usually, when time is short and space is shorter.

Typically, a small job, like a vessel and few

of tie-in points can be collected by one person.

The camera fits in a backpack with the laptop with a small

package of supplemental targets.

How big is the equipment?

No, it is another tool to collect and display information in

3D.

Is it right for every job?