## 5 Conclusions  
ALS offers great potential for archaeological research, but as with any other technology it has its limitations. Because ALS observations can be highly customized to achieve specific levels of performance it is of great important for the researcher to fully understand the technology before diving into a data collection project. The researcher should also be fully engaged during the planning process to ensure that the data products will be sufficient to answer his/her research questions. During the planning phase the main input that the researcher has traditionally provided is the required laser shot density, which has to be clearly differentiated from the return and the ground return density. It is also important to move beyond the concept of shot or return density and start considering how much of the target surface is being illuminated, because it determines the probability of detecting specific features in the DEMs or DSMs. It is also important to remember that while DEMs and DSMs are continuous representations of real surfaces they are produced by interpolating discrete samples that can be widely separated, especially if they are ground returns detected under thick canopies. With regards to canopy penetration it is important to perform tests whose results enable the determination of the flight and sensor parameters that ensure optimal penetration through the canopy and maximize the number of ground returns. For those sites that have relatively short vegetation such as grasses and bushes that are shorter than the pulse length, full waveform ALS is an important option to consider. The data reduction for the production of point clouds and surface models is as much an art as it is a science and the quality of the science that can be done with ALS data is entirely dependent on the quality of the processing. Processing is not a linear process, there is no single best way and it is not a process with a unique end point. In many cases multiple iterations are required to arrive at a product that will allow an optimal answer to the research questions. This is possible only if the data were collected properly, if they were not there is no magic to be done. It is conceivable that as more open source processing tools become available the archaeologists will take over and perform their own point cloud classification and elevation raster generation. Once researchers have taken delivery of their ALS datasets the visualization and analysis options are endless. There is no single best way to visualize or analyze data, it all depends on the quality of the ALS data products and the research question that is to address. Researchers need to be cautious when presented with extraordinary accuracy values, especially when those values ignore basic physical constraints such as the system precision or the resolution of the raw point cloud or raster images. Over the decade and a half that ALS has been accessible to archaeologists it has proven to be an important tool for providing insights into past human presence and interaction with nature at the landscape level. As the ALS technology continues to advance it will provide higher volumes of more complex data. However, perhaps the greater challenge that the archaeological community will face with regard to ALS data is more societal than technical; how to democratize the access to ALS data that has been and will be collected to the broader research community, students and perhaps more importanlyt the general public while still closely guarding the geolocation of those sites that because of lack of protection are subject to looting and destruction. Efforts like Cyark ([[http://archive.cyark.org/](http://archive.cyark.org/)]([http://archive.cyark.org/](http://archive.cyark.org/))) and Open Topography ([[http://www.opentopography.org/](http://www.opentopography.org/)]([http://www.opentopography.org/](http://www.opentopography.org/))) among many others are taking the first steps towards open access but there is still a long way to go.