Digital archiving and on-line publishing of old relief models Mtys - - PowerPoint PPT Presentation

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 1/11

Mátyás Gede János Mészáros

Digital archiving and on-line publishing of

• ld relief

models

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 2/11

• Introduction
• Free photogrammetric surface reconsturction services
• Photographing
• Working with models
• Virtual museum of relief models
• Conclusions, problems
• Further plans

Outline

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 3/11

Relief models

• Usually hand-made or produced in small series
• Vulnerable objects –

digital archiving is very important

• Special digitising tools –

expensive

Introduction

Our aim is to find a method based on freely available technology

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 4/11

Types of 3D digitizing methods

Introduction

• The shape of the object is known, the surface texture is needed
• The shape is acquired by a special instrument (usually based on

laser technology)

• Both the shape and the texture is created from a set of photos

using photogrammetric methods

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 5/11

• Microsoft Photosynth
• Computing is done on our computer
• Only point clouds (no mesh, no texture)
• No downloading

Free photogrammetric surface reconstruction services

• Hypr3D – Cubify Capture
• Computing in the cloud
• Poor performance built-in viewer
• Simple editor is implemented as well
• Autodesk 123D
• Computing in the cloud
• Web or desktop interface
• Selectable resolutions
• Simple editing tools

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 6/11

• Every single point of the surface has to be visible on

minimum two different photographs, and a few parts should be recognisable on several photos.

Photographing

• 8 photos can be enough for an average size model

with no vertical or overhanging walls. (but e.g. Cubify needs at least 10!)

• Flash off, aperture as narrow as possible, tripod.
• Spot lights can improve contrasts
• The camera type is not crucial

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 7/11

Working with models

• Imperfectly reconstructed surface → take more photos!
• Unnecessary parts, wrong orientation and size → rotate, scale, cut!

The products of these web services are only „raw” results! Recommended tool: MeshLab

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 8/11

Working with models

Problems of the texture created by surface reconstruction services (especially Hypr3D):

• mosaic-like appear of surfaces (adjacent faces have textures from

different photos)

• triangles are textured by small rectangular images so half of the

texture file is unused Relief models can usually be represented as 2.5D objects, so models can be „draped” with the „orthophoto”

• f the model. This will improve quality

and reduce model and texture size.

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 9/11

Virtual Museum of Relief Models

• n-line exhibition of digitised relief models
• similar to Virtual Globes Museum
• using the X3DOM framework for displaying 3D objects
• still under construction/testing (only English, few

uploaded models) Temporary address: http://wms.elte.hu/vmrm

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 10/11

Conclusions, problems

Although our method is far not perfect, it can be an option if the digital representation of relief models is desired but there is no financial support for this task. This solution is cheap, and easy-to-use. Limited accuracy

• straight edges and flat surfaces are represented with minor faults

Scalability problems

• the solution that worked well for a 50cm*50cm
• bject was first failed

when it was tried

• n a large (3m*2m) wall relief map

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 11/11

Further plans

• Trying

and examining

• ther web services and/or

desktop applications performing 3D model creation based on photographs

• Improving post-processing possibilities
• Extending the method

to relief globes.

Gede, Mészáros: Digital Archiving and On-line Publishing of Old Relief Models ICC 2013 – Dresden, 25-30th August, 2013 12/11

Thank you for your attention

Further information: http://wms.elte.hu/vmrm/ saman@map.elte.hu messer@map.elte.hu