After a long hiatus too (for reasons of force majeure) back into the ring with the first installment in a series on creating floor plans that I will be alternating with other post on other topics that I have in the pipeline. In this first part will address the general basics
make a planimetric survey from a reservoir, is populated,
cave or in the open air dispersion of materials. In successive deliveries
discuss the creation of floor plans with a computer, the management and creation of
drawings, sketches plants and digging, the different programs (free or free
) and its possibilities, and finally some
advanced techniques such as 3D simple photogrammetry.
treat it as a consequence of the results of the small survey that I proposed in the first months of life of this blog. When asked what topics interested you most, 41% voted for issues related to the excavation, or practical issues. The rest of the vote was: 33% CAD, GIS another 33%, 21% photography, GPS Tracks 8%, and matters related to the PDA's by 1% ("so little interest !!!?).
So what better place to start digging into issues with the creation of floor plans, a very neglected aspect in the training of archaeologists and archaeologists, no doubt, and it has a practical application in excavation.
When I planimetrías I mean the plot at a plane of that is the subject of our profession (mainly archaeological), whether of excavation, exploration or other work. And This blog is about what is, here the term acquired the connotation of how to conduct a mapping of what we are interested in using a computer to be possible with free software and new technologies.
First of all, if you are involved in a project with sufficient money, I do not think, and hire a surveyor. It is certainly the best. However, I advise you not leave him to work alone, and that the best results are obtained by working closely with them.
addition, not all archaeological projects can or require the intervention of a surveyor. For example, survey work is not operating to bring back put the dispersal area of \u200b\u200bmaterials and a pair of structures visible from a reservoir located recently. Or for example, I would like to see a surveyor faces the picture of a poorly maintained home. The archaeological drawing has its peculiarities, let him hear. And finally, the strongest argument. Let's face it: most of our jobs have a minimum budget, in which the participation of the surveyor (with collegiate rates) is not even remotely fit. So things are.
To start on this then, is to have basic notions to make the floor plans. And for this, really there is not much on offer, not many manual (you know) and that I understand that and begin to exist many techniques and methods developed by and for archaeologists who deserve better treatment.
In this post I will focus briefly on some basic techniques for floor plans with few instruments. So little computer. I hope you like.
The objective of this first step in creating archaeological surveying will give a series of field measurements which, conveniently converted into a computer text file can be imported into a program suited to represent.
When we face the problem, in fact, what we get are points located by reference to others. To draw a wall, for example, need at least four points that demarcate the perimeter polygon drawing. When it comes to a line, consists in taking points to draw their path. And for the discovery of materials, a point of situation is often enough.
These points should be placed in relation to something, ie some (or any) reference points (eg zero-P0-).
If the field is unprecedented and has not yet worked with him, just put an arbitrary point in a place that is as visible as possible from the entire area of \u200b\u200binterest. Place another person in addition to ground point (call it raw zero-P0 '-) at a distance known of the first, so I get an axis generally very helpful, and even more if it is well oriented to the north. And finally, also very useful is to create an overall grid site every 5 meters (or ten, or whatever you believe should) so that at any moment we have several nearby landmarks from which to triangulate. Think also that the zero-P0-geopositioned can be at any time by
GPS (or other techniques) so that all the plans that we develop is automatically georeferenced
making a simple translation.
Back then, it is therefore to obtain the status of the other points with respect to our reference points. There are basically four ways: distance and direction (angle), also called radiation, two distances (or triangulation), two directions or angles (intersection) or make the "off-line." You can check in more detail how these techniques are implemented in the help file Mapmaker, in the section on basic principles. There are also several tutorials simple topography page Global Topography. All recommended reading is short, affordable and Castilian.
With these simple techniques and armed with nails or paint (to place benchmarks), a compass and a pair of tape measure will be able to get a planimetric sketch everything that we go to find in exploration. When we want more precision, it is advisable to use the plumb line to keep the tapes as horizontally as possible or take into account vertical angles.
An example of field notes, following one of these techniques (distance or azimuth angle) could be next. Suppose that in prospecting located a settlement which is a small tell, of which there are some walls that define a wall mode. We place our P0 at the top of the tell and began to write:
wall 1 Item 1: distance from P0: X meters angle to the north, and degrees. Item 2 of the wall
1: distance from P0: X meters angle to the north, and degrees. Item 3 of the wall
1: ...
If you have PDA, tablet PC or similar can also be scoring the data in a spreadsheet prepared for this purpose.
A useful tool that I see is underused optical level, present in all excavations (or at least should). Generally used only for the dimensions (or depths) from the zero point. However, many of them have more possibilities. Looking at the bottom of the set, a circle graduated (which can be 360 \u200b\u200bº or 400 º), with which we can measure horizontal angles, like the compass (in fact more accurately). It is guiding the level and protractor to match the north (or the other we are interested, such as P0 ') and place the angle to zero, and from there, pointing to the goal-look, we get a orientation.
On the other hand, if we observe the level optical viewfinder in addition to the vertical line, there are at least 3 horizontal lines will allow us to estimate how far is the look, using methods tacheometric . This distance is obtained by multiplying by one hundred centimeters horizontal line ranging from the top and bottom of the sight. That is, if the top line indicates the lower 198 cm and 188 cm, the distance is 1000 cm = 10 m.
A variant of conventional optical levels are digital, you can automatically get both the z as the distance at the touch of a button. Fired upon a sight that has a bar code, allowing the digital level to do the calculations. They come equipped with other utilities, such as checking if they are out of level, memory, reading, or automatic calculation of the absolute level from ground level. We used the last few years and the truth is that they are highly recommended. Changing
problems in excavation cave we often encounter problems that hinder the implementation of techniques and equipment just to review. First, the optical levels there are difficulties in the dark to read out the sights, or the height of it can not take points there where the roof of the cave is too close to the ground. On the other hand tend to be places or cattery where we can not access to position a tape measure, or where there are slopes that are too high.
For these cases, if you only intend to take heights from ground zero, a level of laser used in the construction (of the bubble) is very effective. The red beam can take the reading levels which impact directly targeted. They are also cheap and if the distances are not great not to be missed very accurately. Moreover, to measure distances in dark or dimly lit nothing better than a laser EDM, combined with a tripod may be the ideal team for our planimetric data in these situations.
Everything stated is executable in a much more accurate and appropriate with a total station or a GPS surveying. The problem with these devices (for us) is that they are complex, and in the case of GPS topographic case should also have good coverage. But since then are the appropriate equipment. So if you have an opportunity to take a course (and this goes to you) do not think.
However, both total stations and GPS surveying with what we're going to get points also are located in relation to other, yes, much more accurately located. The next step is knowing how to address these issues.
This will be in the next installment, where we take what programs can use to import these data and obtain representation on the computer, that after all is what we want.
When we arrived at the post at about 10 am, these three figures were seen flying overhead. 
Before long, a curious young people came to see what happened in the post. 
was a wonderful experience, I never thought that we could see these animals so close and and so close to the City. However, the herdsmen say that this is very common. 