For an experiment purpose i collected 8 projector with 5000 lumens and 1080P resolution. I need to connect them altogether to create a really large image? So, should i use 1 computer for each projector and slice the image and then adjust them to match? Or, is there any hardware and software to help me do this? Thanks in advance.
Do you expect the large image to be seamless, both in dimension and in tone? Each is a separate challenge. Color-matching 8 projectors can be daunting, depending on the technology. As a general rule, you would overlap the images from the projectors and feather their edges. This costs you something in size, with the benefit of disguising mismatches to some degree. Some projectors have this blending ability built in.
In any case, it would probably be better to use a pair of 4-head graphics cards on one computer, rather than 8 separate PCs. Keeping 8 PCs sync-locked is not easy.
There are commercial products like Watchout that will perform the slicing and syncing of one image into multiple playback PCs, if you have the budget for that.
As said by AJ Henderson and Jim Mack, you should just use one computer with multiheaded video. On an X11-based window system, you can use
xrandr to organise the screen segments. Most operating systems have also GUI tools for doing this.
The biggest problem will probably be the fine alignment. Most good projectors have settings for perspective correction built in, but in particular at extreme angles this always becomes troublesome.
If you're projecting from very far away so the area could in principle be covered with one projector (or two) and you mainly need more luminance, it might be easier to use them simply "in parallel", i.e. with the same signal on multiple projectors covering the same area. If they are very close to each other (e.g. stacked – careful that each gets enough cooling!) the parallax difference becomes neglectable.
The easiest way to do this is multiheaded video cards. Many video cards support 3 displays and it is possible to get cards that support even more than that, particularly via DisplayPort (which allows for chaining multiple displays on a single connection).
When using multiple displays in Windows, it will allow you to specify how they are arranged and software can also be used to make it act as one giant display.
Alternately, you can use a stand alone splitter that can take one ultra high resolution output and split it to multiple screens, but it's generally cheaper to simply use one or more video cards to use multiple monitors.
One additional option on Linux setup will be DMX: http://dmx.sourceforge.net/
If enough heads per machine can not be supported and the presentation data is relatively "slow", DMX will provide a single, ultra high resolution X11 display to an application and will automatically split the image between multiple "slave" X servers forming a unified display wall.
If 3D data presentation is desired, VirtualGL supports a "display wall" mode as well (albeit with somewhat more effort): http://www.virtualgl.org/
if you are going for a more profesional look, and have the budget look into pandoras box media servers. They have functionality to not only edge blend multiple projectors, but also map the image onto any 3d object. you might need two of them in order to run 8 projectors but they are much easier to sync up than 8 individual pcs
1 PC with many outs is usually easier to handle than multiple PCs.
Do you have any specific software you're working with? Is it for an installation, or for general use? Do you have a budget you need to stay under? Are they all the same brand and model of projector? Tearing might also become an issue.
As far as software goes, some have been mentioned above, but if you're doing an art installation or similar, these software would be more helpful:
But answering the above questions will help get you more precise answers.