Multipatches, Point Clouds and Meshes

Multipatches, Point Clouds and Meshes

This is our first post from Nicholas Duggan (@dragons8mycat) who writes for xyHt, this article is also posted there.

A Guide to 3D GIS Data Formats

Moving your GIS to 3D is a daunting task. Not only are there all the vertical issues to take into account, but also a whole new world of jargon, which can, at times, be quite overwhelming.   In this post you’ll find a few of the data formats that are most commonly used.

Point Clouds

Also called: multipoints, lidar, multibeam, singlebeam, xyz data, laserscan

Point Clouds

No, these aren’t an awesome punctuation weather dictator, and unless you are using some Kenneth Field colour ramp, you are unlikely to see a rainbow. Point clouds are point data that are vertically enabled (commonly called “z- enabled”).

Typically, when using point clouds within GIS, one would be referring to lidar, multibeam or xyz data whereby there may be multiple points sitting on the same vertical as well as horizontal plane.

Within 2D GIS, point clouds are used as a “heighted raster” where each cell would have the value of the height. The value of using this form of data within a 3D GIS is that the data can be geographically represented in a 3D space so that the information can be viewed rapidly and alongside other risks and issues.

Mesh

Mesh

In the geospatial world, a mesh refers to a 3D image overlay. They’re similar to a TIN; you will have commonly seen these within Google Earth, those buildings that have the uncanny valley effect: they are just a little bit wobbly and the trees appear to be all fused together, but it gives a really nice 3D effect (from a distance). That is a mesh.Within the geo-3D world there are meshes, and there are meshes. I know, we like to keep everyone on their toes, but in reality it is the CAD guys you need to be sore at. Within the CAD world, a “mesh” is a triangulated model, the kind you find in Google SketchUp or you’d print at your local 3D print shop (see Multipatch, below). In the GIS world, we refer to this as a “model.”

Normally these meshes are derived from point clouds, or they can be generated from georeferenced imagery in software like Pix4D.

Popular in gaming, meshes are starting to appear in GIS thanks to software like Google Earth and Cesium.

Polygon Z

Polygon z

This form of data takes the standard 2D topographic data and then “extrudes” it vertically, making it appear like a solid 3D object. This technique is popular for generating mass buildings or creating 3D background information for visualisation. The method is popular due to it being so easy to achieve with the 2D data, which is already used within the software. The only further requirement is a height (to extrude the footprint/data to).Also called: Extruded footprints, heighted footprints

Although this data doesn’t incorporate vast amount of detail, such as windows, roofs, and chimneys on buildings, for example, it does provide a much more accurate visibility analysis and 3D skyline analysis.

The UK’s national mapping agency, the Ordnance Survey, provides its definitive (1:1250) data product, OS Mastermap, in this format and so do some of Open Streetmap as well as GeoInformation Group.

Multipatch

Multipatch

The multipatch, according to Esri, was developed by them in 1997. While I let many learned people fight over that statement, the most popular example of a multipatch is the 3D Buildings found in Google Earth (an example is at the very top of this article) or the kmz models which are generated from Google SketchUp. They are a type of geometry consisting of planar three-dimensional rings and triangles, used in combination to model objects that occupy a discrete area or volume in three-dimensional space. Unlike the “polygon Z,” the multipatch can be complex and have multiple smaller parts to make the whole so are frequently used for representing trees, buildings and street furniture.Also known as: model, mesh

Due to breakthroughs in quadtree, octree and other rendering techniques, the multipatch has gained popularity as massive models comprising of entire cities can be created and presented through the web.

 

“The Barriers to Building 3D Synthetic Environments” at the Transport Systems Catapult

“The Barriers to Building 3D Synthetic Environments” at the Transport Systems Catapult

Last week I attended and presented on behalf of Garsdale Design at the Transport Systems Catapult (TSC) 3D cities event in a foggy Milton Keynes.   This was a “one day opportunity to collaboratively identify challenges and showcase solutions” and “gain insight into virtual/synthetic testing for transport”.

TSC have been having a conversation with us about modelling 3D urban environments using procedural  technologies found in Esri CityEngine and integrating those models in Unity.    I have to be honest though, I was initially concerned about focusing on this negative idea of ‘barriers’ as all we see is opportunities here at Garsdale Design!  However, here was a gathering of people from a variety of industries who understood what it meant to actually make 3D city models and use them in commercial contexts. 

Presentations

The session had some key aims, firstly to understand what a variety of people were doing to create 3D cities, secondly to discuss some the hurdles or barriers of city creation (and publication) and lastly to have ‘round-table’ discussions to identify some of these barriers and how we might overcome them.   Have a look at who came and presented and you can see we had some very interesting presentations!

  1. Transport Systems Catapult : TSC current projects
  2. Future Cities Catapult : Use of environments for smart cities
  3. Satellite Applications Catapult : Satellite
  4. Mantle: Creation of game ready content from GIS data
  5. ESRI : 3D GIS
  6. Leica Geo Systems : Technology behind 3d Lidar Environments
  7. MK Surveys : Creation of 3d Lidar Environments
  8. Garsdale Design : The Art & Science of 3d Cities
  9. UCL : Intelligent positioning within 3d environments
  10. Rust Ltd : Creation of AAA quality game environments
  11. Imsim : Autonomous vehicle fleet management

The event started with an overview of who they were and what Transport Systems Catapult were working on and with.   Catapults as I see them are there to fill the void where companies like ourselves can’t explore or experiment with technologies.  With the best will in the world Garsdale Design hasn’t got unlimited resources to ‘play’ with all the exciting new technologies coming through! 

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Exciting things to watch for from us this year

Exciting things to watch for from us this year

 

After a period of ‘radio silence’ I’m looking at doing more regular postings here.  As I’ve discussed before this blog is naturally a semi-official Garsdale Design blog as well.  As such we’re looking to have our Southampton colleague Nicholas Duggan contribute every so often.  Nick (or @Dragons8MyCat ) is a well known blogger and the European Editor for XyHt magazine as well as having vast GIS and mapping experience in the Nuclear and off-shore industry. 

Garsdale Design’s work in 3D GIS is well recognised in the Esri world, I’ve heard us called the ‘3D-Guys’ more than a few times from separate people/organisations now.  We’re looking to capitalise on our knowledge by creating a new brand (which will be launched soon) to separate ourselves a little from Garsdale’s Architectural, Planning and heritage business.   We’re also on the cusp of launching (subject to some bureaucracy, don’t ask) a 3D data service for people who just want their 3D basemap now.   If you’d like some more details you can contact us directly.

If you’re an Esri user you should start looking at ArcGISPro seriously now

We’re getting increasing numbers of enquiries for CityEngine and ArcGISPro training, not least because we are the official EsriUK CityEngine trainers!  I think this is mostly down to increased awareness of the 3D capabilities of the Esri platform (have you tried ArcGISPro yet??).  Planners seem to especially ‘get’ Esri CityEngine.   Also whilst there is much talk of BIM more and more organisations realise that BIM doesn’t sit in a vacuum and often requires GIS.  BIM is 3D and so knowledge of 3D GIS is required.

This year we hope to organise a geospatial mini-conference here in Cumbria, with some speakers and followed on by a couple of days of training/workshops.  If you’re interested in getting involved or coming along please get in touch.

Keep on the look out for our new brand, we’ll do a blog post here on launch day.  In the meantime if you need Esri CityEngine or ArcGISPro training contact us!

CityEngine Rule of the Week

CityEngine Rule of the Week

It’s been a while since I’ve posted I know! Anyway this year the CityEngine team at Esri have been publishing ‘Rules of the Week’ videos not only that they’ve been publishing the actual rule files as well.

A great way to learn CityEngine is to look at the code other people have written, and who better to (ahem) copy form than the CityEngine team itself.

It’s a bit of a shame that the audio quality is so good in places but if you like CityEngine it’s well worth a view!

Revisiting Cartographers Toolkit for CityEngine

Revisiting Cartographers Toolkit for CityEngine

peterson4
A longtime ago in 2013 I did a video demoing some color pallettes being used in CityEngine, I’ve decided to revisit that work making it compatible with CityEngine 2016.1 and adding additional features.  The rule now ramps Peterson’s colours based on building elevations, assign your rule and then choose the page number of your favourite Palette in the Cartographers Toolkit (just the palettes obviously) and click generate.  The rule uses CityEngine’s ability to query lists of data to make it all work.

peterson_tool

I always love CityEngine’s ability to become a flexible symbology tool, I may make this a rule package for use in ArcGISPro too.