About Photogrammetry

Photogrammetry refers to the practice of deriving 3D measurements from photographs. See our page describing photogrammetry, how it works, and examples. More…


Updated, Summer 2016: Calibrated Scale Bar Placement and Processing Tips

Agisoft tips and tricks document

Agisoft, the maker of PhotoScan software, has published a support document — updated in the summer of 2016 — authored by the CHI team, Guidelines for Calibrated Scale Bar Placement and Processing, to assist users who are applying calibrated scale bars in a 3D project. More…


Photogrammetry Training Class

Photogrammetry class

CHI offers a 4-day photogrammetry class for groups of up to 15 people. Get practical experience in acquiring photogrammetric image sets and producing scientific 3D documentation with demonstrable accuracy. Learn imaging equipment, capture setups, and software to build 3D content. More…


Need Some Help?

Let CHI experts advise you on your imaging challenge. CHI offers customized consulting services to both institutional and private clients, with special rates for nonprofit organizations. Projects of all sizes can be accommodated. Learn more…


Question? Ask on the CHI Forums

CHI offers a free discussion forums site where you can share your questions, insights, and issues as you practice photogrammetry. Join the conversation!


Calibrated Photogrammetric Scale Bars

Contents:  What they are  Why they are unique  How to order  Product details 

Cultural Heritage Imaging (CHI) is now offering a set of professionally calibrated scale bars for highly accurate measurement during scientific photogrammetric imaging of 3D data. These scale bars are uniquely suited to today's practice of close range photogrammetry. The unrivaled scale bar design was developed and field-tested by a senior team of photogrammetry experts from the US Bureau of Land Management.

What Are Scale Bars and Why Do You Need Them?

Photogrammetric Scale Bars from CHI

Calibrated photogrammetric scale bars from CHI (see details below)

Scale bars are flat, lightweight linear bars in several sizes with printed targets separated by a known distance. To enable the measurement of an object or a site in 3D you place the scale bars on, around, or next to the imaging subject. (The scale bars ship with a user guide that has detailed instructions). When a series of images is processed to create a 3D model, the processing software — we use Agisoft PhotoScan Pro — finds the exact center of the targets on the scale bars in the set of photos. Once the professionally calibrated, written measurement of the distance between the targets, is entered in the software, the measurement of any feature of the imaging subject becomes possible.

Why CHI’s Photogrammetric Scale Bars Have Unique Value

These aren’t just any scale bars! Our scale bars are:

See details about the scale bars below.

How to Order a Set of 10 Calibrated Photogrammetric Scale Bars — $495

Note — We cannot accept a scan or photo of your order form, so please be sure to follow these instructions:

To order, download the appropriate order form below. Open the form in the free Adobe Acrobat Reader application, and type directly into the fields. Save the form and send it to scale-bars@c-h-i.org. Please be aware that many web browsers do not properly handle PDF forms, so you should always use Acrobat Reader.

Download the US Domestic Order Form (PDF)
Download the International Order Form (PDF) 

The price of each set of scale bars is $495.00 plus a cost of between $15–$23 for UPS ground shipping in the US, depending on the destination. We charge sales tax for scale bar sets shipped within California.

We ship internationally via USPS (United States Postal Service), which transfers the package to your country's local postal service for delivery. if you prefer to use a different carrier, let us know. To determine international shipping and handling costs in advance, contact us at scale-bars@c-h-i.org.

We can accept credit cards, Electronic Fund Transfers (EFT), checks, and purchase orders. If you choose to pay by credit card, we will send you an invoice that includes a link to enter your credit card information using a secure server. At that time you can pay with any major credit card or with a PayPal account. Please let us know what you prefer.

If you have any questions about the scale bars, please send an email to scale-bars@c-h-i.org; include your location if you have questions about shipping. If you need to have your department information and/or a purchase order number included on your invoice, please send us that information, and we will email an invoice back to you. We will ship your scale bars to you after we have received payment or a p.o. number from your institution.

Scale Bars Details

CHI provides a set of 10 scale bars: 2 each of 5 sizes, 6 coded, 4 non-coded.

Coded Scale Bars

Three sizes of the scale bars have 12-bit coded targets. The coded targets are automatically detected and named by several photogrammetry software packages, including Agisoft PhotoScan Pro. The automatically detected names (represented by numbers) of the coded targets are different on all the bars in a set, and CHI offers 10 different sets with unique coded targets. This is useful if more than one set of scale bars is needed in a project. The different target designs ensure that the processing software can manage those targets as unique and not confuse them with other targets within the same 3D project.

Non-coded Scale Bars

The non-coded targets come in two styles.

Specifications of Each Type of Scale Bar

Note: Our scale bars are calibrated by CHI staff to 1/10 mm accuracy or better, with the actual calibrated measurement between each target written on the scale bar.

Meter Scale Bars (2)

Meter scale bar

Each bar uses 3 coded and 2 non-coded circular targets. Centers of each target are approximately 25 cm apart, with a total distance from targets on each end of 1 meter. Each bar’s overall dimensions are 108cm x 6cm tall.

Half-meter Scale Bars (2)

Half-meter scale bar

Each bar uses 3 coded targets. Centers of each target are approximately 25cm apart, with a total distance from targets at each end of 1/2 meter (or 50cm). Each bar’s overall dimensions are 60cm x 6cm tall.

Quarter-meter Scale Bars (2)

Quarter-meter scale bar

Each bar uses 2 coded targets. Centers of each target are approximately 25cm apart. Each bar’s overall dimensions are 35cm x 6cm tall.

18cm Scale Bars (2)

18-cm scale bar

Each bar uses 2 non-coded, circular cross-type targets. Centers of each target are approximately 18cm apart. Each bar’s overall dimensions are 23cm x 6cm tall.

5cm Scale Bars (2)

5-cm scale bar

Each bar uses 2 non-coded circular cross-type targets. Centers of each target are approximately 5cm apart. Each bar’s overall dimensions are 10cm x 6cm tall.

Questions About Scale Bars?

Please send email to scale-bars@c-h-i.org.

Note: The calibrated photogrammetric scale bars come with a limited warranty. Read the warranty…