Disclaimer: these software programs may not be free indefinitely, even if they are free at the time of print. There are many trials of products, such as Photoshop (useful for editing photos, which can be used in modelling), but much of the free software is also constantly being updated/ is freeware, and so may contain bugs, so it may not work properly.
3D modelling software does what it says on the tin; it allows you to create 3-dimensional models (if you know autoCAD, you can skip straight to the software section below
A lot of worries and criticisms I have discussed with fellow archaeologists is that there is not enough time to incorporate modelling into many projects, because either the software will not be supported, or the software has to be learned, and this will take time away from the project and actual excavation. These are valid criticisms, but for a project that involves a large and/or public audience that will find this information online, I argue that a model created using free software will not take very long to learn, the time and financial costs involved are very low, and most computers will be able to handle simple models. Compared to software that you have to pay for (such as AutoCAD), many of these software packages are not very advanced, nor do they provide some of the measuring tools necessary for a detailed reconstruction. But, at a time when the world has been undergoing a social and technological revolution since the creation of the internet, archaeology is being left behind in the technological front. but as a compensation, while we have always taken the hand me downs to begin with, such is the rate of development, in this situation the "hand me down" is free and I recommend it to archaeologists the world over, not least because a lot of these software packages are compatible with each other, especially when it comes to publishing!
However, one thing that will have to be considered when you build a model is how you actually, well, build it. some complex lines and geometries need to be "thought through" before you start building it up (see fig.1). For example, to build an angular roof that fits a circular building, you will need to think about how to create the height of the roof, and how to model any inconsistencies in the roof. This also leads to the question of just how much detail you want to put into the model (down to the individual brick, for example, or just the walls), which details will be left to the textures (think of textures as coasts of paint for buildings, but can be applied to anything)?
- Can you photograph it from all angles freely (excluding the bottom, but would be nice if you could)?
- If this isn't possible, can you get hold of more advanced techniques, like laser scanning, instead of photography?
- Is it appropriate to create a virtual model of the object? If you're only going to use it for presentation, that fine, and these free applications are great, but you may not be asking the right archaeological questions if this is your primary focus. Ask the archaeological questions first, then think about how to model it.
- Are there more appropriate methods available for what you want to model?
- If this isn't possible, can you get some surveyed points of the object and hope to photogrammetrise it?
- Most importantly, can it form the basis of your research question?
- SketchUp - very good for starting out on modelling in general, but doesn't contain many advanced functions in the free version. Because it is so simple, it is very easy to model large areas quickly, without using up much disk space. You can also add some textures, so a very convincing model can be built up quickly. It is better for modelling buildings, rather than smaller artefacts. It also doesn't allow you to import photos, but it can import snapshots of, and georeference to, Google Earth! as a results, it is very tempting to show excavations or known positions of buried features alongside standing features. Combined with it's own online depository, this means that it is very easy to find multiple models very easily. The greatest problem is when complex architecture (such as creating a finial, see fig 3 below) or smaller artefacts. There is also very in the way of photogrammetric functions. BUT, my main criticism is what Google will do with the data, particularly once it is on their depository (Google sold SketchUp in 2012 to Trimble, but Google still release a free version). Will your model put on Google Earth without your permission, for example? In this increasingly Big-Brother style world that Google is turning us into, are we unwittingly giving Google the very data it needs to accomplish such a task?
- FreeCAD- this requires more knowledge to work than Sketchup, because FreeCAD can implement advanced motion simulation capabilities, so you can do some fancy things, like make a moving water wheel. It is not as intuitve as Sketchup though.
- 123D catch and make- This is a suite of programs made by a large company (AutoDesk), they has an interface similar to autoCAD; i.e. they have a viewcube, the mechanics are reasponably intuitive too (although if you haven't used autoCAD, then SketchUp may feel more intuitive). It works mainly with dwg files made by autoCAD.
- Cultural Heritage Imaging have been pioneering unique photogrammetric techniques in the USA, and their free software is called Reflectance Transformative Imaging (aka RTI). As it has been specifically designed with cultural heritage specialists and archaeologists in mind. However, if you have never used photogrammetric techniques before, then it is worth going over to their website and reading their manual, because it has two programmes that you can download. The methods employed are easy to understand, but the steps in the program (RTIviewer) tend to feel a bit dislocated from the process of actually stitching the photos! Don't worry, this happens, and if you follow the instructions in their manual, you will get a results. This is probably the best photogrammetric software; however, it is highly recommended to read their website first and then employ their methodology (instead of their capture kit, you can get similar results, using a shiny ball, string and a tripod for most artefacts/ faces). So this software requires the most planning too, but the results are worth it. One example of RTI being practised in the UK is the Saving Your Cemetery or Church in York.
- 123D catch-autodesk's photogrammetric software. I haven't tried this, so I can't give my opinion!
So to summarise, if you think that you could model a building, the chances are that there will be a software package for you, that will be free, easy to learn, can be downloaded to your home PC. SketchUp is recommended if you don't mind sharing your models, but other freeware is available, that can do the job just as well.