Introduction 3D Model - The Leicester City model is a photogrammetric survey based 3D representation of 380ha of Leicester s Central Regeneration Area. The model is to be: Used for marketing and inward investment activities, including presentations, websites and social media Used as a key tool for community engagement, as a visual aid to encourage feedback on development proposals; Used by our urban designers, highways engineers and 3rd party architects to help develop and refine the design of key development projects and support them through the preplanning process. It will be owned by Leicester City Council and maintained by the producer with necessary licensing arrangements to support uses and new workflows It will be an inclusive and interoperable tool, able to incorporate and be compatible with any major separate software assets that users may have Able to be extended at a future if and when required. This model incorporates the 3D ground profile macro relief, 3D building envelopes, micro-relief walls, fences, point features such as poles and signage (in generic form), individual trees and/or area landscaping and 3D building envelopes. The model thus provides an accurate 3D virtual world with which the council or its agents may interact with.
At the core of this model is an accurate 3D mapping extracted from stereoscopic photography and IMU data provided by Leicester City from an external sub-consultant. The model is optimised for speed of use and rendering and can be loaded or imported into most leading 3D packages. The entire model or elements thereof have been designed to run on even a modest modern computer. While we encourage the use of the model by third parties it is essential that information provided back to the Council for inclusion into the master model be well structured so as to maintain the flexibility and operability of the entire model. These guidelines will aid in minimizing the amount of work required to update/maintain the master city model. False Origin The model is geo-referenced to OSGB national grid and level datum but utilises a false XY origin to provide compatibility with certain software packages and lighting systems. This model is at 1:1 and in meters. The false origin is located approximately in the centre of the 3D model. The false origin for the Leicester city model is: -458500, -305000 General Information provided to the Council for inclusion into the city model shall follow the guidelines detailed below. In general everything should be tied into the current city model in position, rotation and scale, in a format which is compatible and a quality similar to that of the original model. The model is in meters. Optionally a party may wish to also provide their base full resolution high detailed model. We are happy to accept the same but this must be additional to the base model since its level of detail will most likely effect the performance of the city model as a whole. It is suggested that you contact the undersigned to discuss any specific queries you might have. Geometry: Site works / DTM The existing DTM is made of separate 3D mesh objects for: roads, water, kerbs, paint markings, white/yellow solid/dashed and finally other items. Standard materials are applied to all but the last other items which take their texture from the global orthophoto (plan accurate photo map) imagery. The city 3D triangulated mesh is a fully welded. It is generated from a combination of random spot heights and 3D breaklines (which themselves may be 3D features such as road edges). In the case of city models much of the DTM will be formed by the breaklines rather than spot heights, the opposite occurs in more rural or park areas. All breaklines shall be dynamically segmented at intervals of not more than 5m when creating the TIN.
DTM information provided should be tied fully into the 3D model and matched at a triangle boundaries. A 3D bounding polygon shall be provided. The base textures used for standard objects should be those already provided in the 3D model. It is also helpful if the original 3D point and polyline information used to produce the TIN is provided as an aid in checking, in 3D-CAD (DWG or DXF formats) Special or unique textures may be applied to specific areas of your DTM. Please refer to the Textures and data formats sections below. Buildings The 3D model of the building shall include the external envelope of the building. Major visible internal elements may need also to be included especially in the case of glass building façades. The model shall be an accurate representation of the development tied fully into the 3D model. All nodes in the mesh shall be welded. The model shall be fully coordinated and in meters. The external shell shall be a single object with a single multi-sub material The internal elements may be a separate object with an additional multi-sub material. If the project consists of a number of separate structures these may be provided as separate objects. Face mapped façades rendered from a higher specification 3D model are also acceptable. Models shall designed so as to keep the number of nodes and triangles to a minimum. A CAD (DWG or DXF) plan drawing of the development is useful to ensure that the model has been accurately located. Full detail models can be provided as additional information to the above. Please ensure that the
naming convention of any such model is clearly defined so that detail superfluous to specific Council requirements may be turned off as desired and with ease. Any information provided to explain the model shall be given in DOC or TXT formats. Data formats, and textures shall follow the guidelines below. Landscaping hard and soft Global landscaping should reuse the simple 3D trees and hedge textures provided as part of the base model. Specific landscaping features may be incorporated but these shall maintain a level of complexity similar to that provided in the base model. Nodes and Meshes should be kept as small as possible. Full detail models can be provided as additional information to the above. Please do not provide tree or hedge models with individual leaves. Please refer to the Textures and Data Formats sections below. Textures/Materials All textures relating to a specific proposal shall be provided as multi-sub materials. Textures shall be provided in one or two forms. Textures for models to be incorporated into the global model shall be kept small, typically 1024x1024 or 512x512. Textures shall be provided in Jpeg formats. The use of texture pages is recommended to reduce the number of files which have to accompany your proposal. Materials shall be simple, no bump, normal or displacements maps Textures should be re-used wherever possible to reduce overheads on the Council IT structure. Textures for a project specific model are not limited to a maximum resolution limit. Please, however, exercise restraint and consider the use and equipment available at the Council offices. The council requirements are to utilise your model as outlined in the opening statement.
Data formats All information (files, objects, textures, texture images, etc) relating to a specific proposal/project should be prefixed with a unique identifier so that the relevant elements may be quickly identified. The naming convention of files, objects, textures provided should be clear and in plain English. All mesh/object information shall be collapsed to its raw state. No modifiers shall be left on stacks. All nodes shall be welded. Nodes and triangles shall be kept to a minimum. Objects and materials shall be kept to a minimum. Where possible objects shall be combined and material ID used with multi-sub materials. Specialist rendering add-ons shall not be used. We suggest that files be exported and provided in a number formats. Often specific elements between software packages fail to translate so providing a variety of formats allows the flexibility of choice. The base model is maintained in 3DMAX v2012 and this.max format is always acceptable on its own. Additional 3D formats which can be utilised are: fbx, 3ds, sketchup and dwg. 3 rd Parties should provide with their submissions a number of rendered stills or animations of their model from their own 3D packages. Plan / Elevation information in CAD (DWG or DXF) may also be useful. These can be used to confirm that all elements and textures have translated correctly. For further information please contact Chris Shackleton at D3D - DigiTech 3D +353-1-8135000 chris@d3d.ie d3d-dublin