hi fellas, we do architectural visualization work in my studio but not the real time interactive walkthrough yet.
we are planning to invest some time and money in this field as we see that the market is there but i am still not certain which solution to choose from. right now its between unity3d and quest3d. it seems pretty simple in both of the solutions to import a model put lightbaked textures and drop an fps camera and just walkthrough the model. but we need more, we need the model to be interactive in a way that a user can change certain things in it, such as change the color and textures of walls, change some furniture from library etc. I have seen some example and it looks like it is possible in both unity3d and quest3d. while i have some idea how this can be achieved in quest3d, i still have no idea how this level of interaction is achieved in unity3d, do we need advance knowledge of programming to develop something like that?
thanks for reading the long post, hope you guys can help me decide.
Well it is definitely possible in Unity, and not too hard.
I think you could also even use the free version when you work with baked lightmaps.
Swapping colors and textures of models is quite easy using the renderer.material commands.
You could script either in JavaScript or C#, i don’t know if you are familiar with one of it but there are a good amount of tutorials too.
I think these kind of projects don’t really need a lot of programming, it’s almost just about art.
Also, i don’t know if Quest3D can do it, never actually used it or read much about it, but you can also run your visualization in a webbrowser and make changes using the website if it’s somehow useful in your case.
1st of all, no need to invest. At least money. You can do all those things with the free version.
Should be fairly easy create a gui and then have it change the materials color or texture. Also you can also ask for help here at the forums or at unity asnwers. And if money isn’t a problem, you can ask for somone to make this simple script for you in the collaboration section.
Welcome 
so in conclusion, those type of interactivity require knowledge of programming language, am i right?
Yes but not a lot actually.
Hiring someone to program this shouldn’t be too expensive either as this is a short task.
hey thanks for the suggestions, hiring someone online would be difficult since we need someone to be present in our studio, and it becomes difficult to coordinate online when there are many projects involved.
Well there are many programmers from different countries so it depends on where you are located and you might find a programmer who can work “indoor”.
The CharacterController right out of the box will work for you. The scripts are written already and it really isn’t alot of code…say 20 lines or so for the CC. Get the free version and toss a CC onstage with one of your models. The assets pipeline for art cannot be beat AFAIC.
HTH
Unity is very good for Archviz and very powerful for the features you require.
Are you or any of your designers coded minded people or wishing to become one one? if not, then the features you require won’t seem that easy other than dropping the first person controller in your scene.
A programmer posting on an artists forum asking is it easy make a house with realistic textures would recieve the same “its easy” answer. But like everything it either takes time to learn or you need a mindset for it.
Don’t disgard the idea of using external programmers. I have worked with my main programmer for over 4 years now and we live on opposite sides of the planet. I have others working on projects for me at present. This forum has an abundance of talented programmers for hire or to help and it only takes a post in the job forum to seek a quote for what you require. It will allow you to hit the ground running and get your studio into the interactive arena much faster than you thought.
http://www.3dbuzz.com has a great free 7 hour Unity/C# video training course, perfect for a designer to get a feel of coding in Unity if you are interest in pursuing it.
I tried Quest3D before getting Unity some years back and am very happy with the choice I made 
I’m not sure what your threshold is for programming, but the kind of model and texture swapping you want to do is probably among the easiest things to script.
I’m doing the exact same thing, even with the possibility to interact with the environment, mesh swapping, texture swapping and so on…previuosly I used to do all this stuff with another engine ( Esperient Creator ), but since that engine is almost gone I decided to switch to Unity, even because the new render features ( deferred rendering, Beast lightmapping and lots of cool stuff ) make it one of the best next-gen engine.
I’m just a 3d artist, doing all the programming all by yourself could be a really pain in the… if you don’t have time to learn ( like me ).
I already ask for paided collaboration about doing all this stuff…I received good prices, and the good thing is that you probably need to invest just once on those features that you ask, then you can use them again on other projects, so fair enough 
You just need to invest a bit of time in your real-time walkthrough, understand all the mesh and rendering optimization, how to use lightmaps, and so on…so basically you need to try a lot, but if you have a ready-to-go job to work with, I don’t think you’ll spend so mush time to find a good solution.
Features are great, the community is huge, you can even publish and sell your works with the free Unity3D edition, what are you waiting for?
Quest3D is a very powerfull engine, but is definitively hard to work with, especially if you’re not a programmer or understand very little about visual script…I tried to work with it but I let it go after a while…Quest3D is not that cheap too, so before spend almost 10k for that engine download Unity3D and start to play with it, you wont regret .
thanks a lot guys for your valuable comments, your have helped me made up my mind, i have decided to give unity3d a go and lets see where it gets us.
thanks and regards
I have never heard someone regretting their choice when going with Unity.
Just look how many big names are using Unity engine right now. BBC made a robin hood game. Also there is a visualization of the oil leak catastrophy done with Unity. EA made Tiger Woods online game. NASA is using Unity with their visualizations.
If you make visualizations for web then the plugin penetration is important too. Every month there are 2 million unity plugin installatsions world wide. Also when in future Chrome browser wont require Unity plugin it will add 70 million potential users.