The most common delay in visualisation projects has no technical cause. It arises because the source documents are incomplete, contradictory or delivered at the wrong stage of maturity – and because this only becomes apparent once the model already stands.
For developers, project managers, architects and agents this is avoidable. Which documents a visualisation studio actually needs can be described in full in advance. This article does exactly that: structured into mandatory documents, useful additions and special cases, with an honest account of what is missing when something is missing.
Why the question of documents decides the deadline
A rendering is a simulation. Everything that is to appear in the image must be described beforehand as geometry and as a material property. The software cannot supply anything that has not been defined. If a specification is missing there are exactly two possibilities: it is queried – which costs time – or it is assumed. An assumption that later turns out to be wrong costs more time than the query would have.
The second reason is timing. Changes are close to free at the start of a project and grow more expensive with every stage of work. Swapping a facade colour before materials have been assigned costs minutes. Changing a storey height after furnishing, lighting and cameras are in place means repeating substantial parts of the work. Reviewing the documents at the outset is therefore the most economical step in the whole process.
The mandatory documents
No reliable rendering can be produced without these.
Floor plans
Floor plans of every storey to be depicted, dimensioned and at the currently approved design stage. They supply the horizontal geometry: wall runs, wall thicknesses, opening positions, room layouts.
The format is decisive. A CAD file – usually DWG or DXF – can be used directly as a basis in the 3D application and is dimensionally accurate. A PDF is valuable as a checking document but more laborious as a sole basis, because it has to be traced. A photograph or a scan of a paper plan is the worst option: scale distortion from scanning is the norm, and the dimensioning is often not consistently legible.
Where possible, supply both: the CAD file to work from and a PDF for cross-checking. With the PDF it matters that it corresponds to the CAD state – two versions of the same floor plan that differ are worse than one.
Sections
At least one meaningful section, preferably two in different directions. The section supplies the vertical geometry: storey heights, slab thicknesses, floor build-ups, parapet heights, lintel heights, roof pitch, parapet level.
This point is regularly underestimated. Floor plans alone contain no height information. Without a section all heights have to be estimated, and errors in estimated storey height are clearly visible in the finished image: rooms look compressed or over-tall, and windows sit incorrectly in the facade.
Elevations
All facade elevations that will be visible in the image. They show the arrangement of openings, changes of material, cornices, projections, window subdivisions and the treatment of plinth and roof edge.
Elevations are at the same time the most important checking instrument. Contradictions between floor plan and elevation – one window bay too many, a door in a different place – only emerge when they are compared. It is normal for such discrepancies to exist; what is not normal is discovering them during the correction round.
Material and colour specifications
A material specification is needed for every visible surface: facade, plinth, roof, window and door frames, railings, external stairs, external floor surfaces. For interior renderings, additionally floor coverings, wall finishes, doors, sanitary ware and, if depicted, kitchen fronts.
The most usable form of such a specification is a manufacturer or product designation – a colour number from a render system, a brick type, a roof tile model, a RAL shade for window profiles. A specification of that kind is unambiguous. Formulations such as "warm grey" or "light timber" are not, and reliably lead to a correction round.
If you have not yet decided on a given point, say so explicitly. A deliberately open point can be planned around; an unspoken open point gets closed by an assumption.
The construction specification
The construction specification is not a formality but the substantive basis for checking. It sets out what is actually owed – and the rendering should show precisely that.
Practical experience on this is unambiguous: images that show more than the specification provides for create friction at handover. A depicted fireplace with no flue in the plan, parquet instead of the vinyl that is owed, a roof terrace that does not exist. Supplying the construction specification enables the visualiser to notice and raise such discrepancies rather than unknowingly producing them.
Useful additions
These documents are not mandatory but improve the result considerably.
Landscaping and external works plan
In exterior renderings the surroundings determine the image at least as much as the building. A landscaping plan supplies paths, access roads, parking, boundaries, terraces, planting and the run of the terrain. Without it, the surroundings are created according to the visualiser's design judgement – which may look good but may have nothing to do with what will be built.
The terrain is particularly relevant on sloping sites. A building on a slope looks completely different depending on how the ground meets it. Level information or a terrain section resolves this problem.
Site plan with north arrow and neighbouring buildings
The site plan is needed for two things: the correct orientation of the building – and hence a physically correct sun position – and the surrounding development.
The sun position is where care pays off most quickly. When location, orientation, date and time are known, the light can be simulated as it really occurs. A south-facing terrace in afternoon sun is then a demonstrable statement rather than an assertion. Without a north arrow, the light gets set for pictorial effect – and a prospective buyer who discovers at the viewing that the terrace faces north has legitimate grounds to ask questions.
Photographs of the surroundings
For new buildings in an existing context, photographs of the site and its neighbourhood are extremely valuable. They show what plans do not: the actual character of the neighbouring buildings, vegetation, street furniture, the materiality of the setting, sight lines.
Simple shots taken from the intended camera positions, with location and direction of view noted, are useful. They make it possible to check whether a desired view is possible at all – or whether a tree, a wall or a neighbouring building really stands there.
An existing 3D or BIM model
If a 3D model exists, supply it. As a rule it saves the shell and speeds up the start considerably.
A realistic expectation matters here: a planning model does not replace the visualisation work. It is built for planning purposes and contains component and layer information irrelevant to image computation, while lacking many details that affect the image – profile cross-sections, joint patterns, handles, seals, transitions. The model is a starting point, not a finished result.
State as well which format you are supplying and which software it came from. Formats such as IFC, FBX or SKP behave differently on import, and the level of detail carried across depends on that.
Reference images
Two to five images you like, each with a brief reason. The reason is decisive: "I like the lighting mood here" or "this furnishing suits the target group" is usable. An image without comment leaves open what was meant – view, colour world, furnishing style or post-production.
Negative examples are equally useful: images you expressly do not want. They narrow the design space faster than positive examples do.
Special cases
Existing buildings and extensions
If the rendering is to show a new build adjoining an existing structure, reliable geometry of that structure is needed. Old record drawings are frequently unsuitable: they depict the planned rather than the built state, and alterations accumulated over decades are rarely fully recorded.
If the rendering needs to be sharp at this interface – connection heights, eaves lines, facade alignments – a 3D survey of the existing building is the more reliable basis. The effort involved is modest compared with an image that misrepresents the junction.
Interior renderings
For interiors, information is needed that plays no role outside: clear room height, window sill heights and dimensions, door sizes and opening directions, positions of radiators, sockets and switches where these become visible, and kitchen or bathroom layouts if these are to be depicted.
A statement about the target group is a helpful addition. An apartment for families is furnished differently from an investor unit or a penthouse. Making this decision early saves an entire furnishing round.
Refurbishment and conversion
With refurbishments the starting position is different: the building exists and can be photographed. Current photographs from the intended views are valuable here, as is a clear delineation of what will be changed and what stays.
That delineation is the critical point. A rendering showing a refurbishment is read by viewers as a statement about the target condition. If the facade looks new in the image although it will not be touched, the statement is false.
What you do not need to supply
For completeness: structural calculations, building services drawings, fire safety concepts, thermal performance certificates and bills of quantities are not needed for a rendering. They contain no image-relevant information and only add to the review effort.
There is one exception: if building services are to be visibly depicted – ventilation outlets in a hall, sprinkler heads, exposed pipework in an industrial building – then the corresponding drawings are relevant.
Limits and typical mistakes
Complete documents do not guarantee a good image. They are a necessary, not a sufficient, condition. Design, material work and lighting still determine quality.
The wrong design stage is worse than a missing drawing. A missing drawing leads to a query. An outdated drawing not labelled as such leads to a wrong model that only comes to light late. Label design stages with a date and a version number.
Contradictions between documents are the rule, not the exception. Floor plan, section and elevation rarely agree completely. That can be dealt with – but it must be resolved before modelling, not afterwards.
Commissioning too early creates duplicated work. A rendering based on a preliminary design depicts a state that will still change. That can make sense, for instance for a site enquiry – but then deliberately, and with a correspondingly abstracted depiction.
"Just make a suggestion" is expensive. Missing requirements are replaced by assumptions. Every assumption that does not match your idea turns into a correction round. A twenty-minute briefing usually saves an entire one.
Documents supplied late are the most common cause of missed deadlines. If an updated floor plan arrives after the model has been signed off, part of the work already done is void. Assemble the documents in full before commissioning.
Without a named decision-maker there is no sign-off. Feedback from several departments frequently contradicts itself. Nominate one person who consolidates correction requests and approves them.
A practical checklist
Before commissioning you should have: floor plans of all relevant storeys as CAD and PDF at the approved stage; at least one section; all visible elevations; material and colour specifications with product designations; the construction specification; for exterior images a site plan with north arrow and a landscaping plan; where there is an existing context, photographs or a survey; two to five annotated reference images; a statement of the desired views; the required output formats and resolutions; and a named contact with authority to decide.
Output formats are the item most frequently forgotten. Resolution is set before computation. If an image is computed at portal resolution and you later want to print a site hoarding from it, you need a recomputation.
Conclusion
The question of documents is not bureaucratic preliminaries but the stage of work with the best ratio of effort to effect. Supplying floor plans, sections, elevations, material specifications and the construction specification in full and at the right stage measurably shortens the project and avoids the expensive late corrections.
What you do not yet know may be left open – but say so. An explicitly open point gets decided jointly. An unspoken open point gets closed by an assumption, and assumptions are the most common cause of correction rounds.
You will find the scope of services and the workflow under property rendering.