ReefMaster: Curados Project (2/2)

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TOPIC: Curados Project

Curados Project 12 years 5 months ago #715

AnglingCharts
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Guys,

we need to be careful here. Vector graphics, while being supremely convenient, have serious drawbacks, particularly for the uninitiated. The accuracy of ANY chart depends solely upon the scale of the data from which the chart is derived.

If you make a vector chart with a shoreline based upon Google data where the size of a car was the size of a pinhead then by using that vector chart at levels of zoom (magnification) higher than the level at which it was drawn you are not getting any more accurate, its getting LESS accurate. In fact you are creating an ambiguity which is not going to be obvious to anyone other than the person who made the chart.

Raster charts are of such a nature that this kind of problem is immediately obvious.

So its horses for courses. Vector charts are NOT more accurate - they are just completely different. A vector chart is just as accurate as a raster chart at the same scale. If you want an accuarte chart then you need to do an accurate survey !

T

http://www.anglingcharts.com/

Mucking about in boats

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Curados Project 12 years 5 months ago #727

gpiverson
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The benefit of vector is reduced size, query-ability, and variable displays (turning stuff off and on). With any vector, there will usually be generalization and rounding that may throw off some results as well as the vector always being generated with a scale in mind.

That said, if I can convey the message equally well as raster or vector, I'll almost always go with the vector approach for the above mentioned reasons.

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Curados Project 12 years 5 months ago #733

Curado
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AnglingCharts wrote:

You can create anything you want. You simply need to create shapefiles in a GIS application (QGIS is free) or GPSMapedit, and include them in your fileset in IMC. I would suggest a different shapefile for each object type.The new attribute facility in IMC will sort out the attributes for you. You'll need the manual.

Good luck

Trevor

Edit - If you wants a small tutorial on how to do this kind of thing I'll put one on my website. You will need the original data that you created the lcm with.

A tutorial would be great Trevor.

I lot of info to play around with, thanks everyone.

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Curados Project 12 years 5 months ago #735

fjordfisher
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Proposal:

Trevor should make tutorial for Mapedit and i for QGIS.
But what is the starting point and the target?

I think start should be a shape, that contain only depth lines with values and target could be a ready attributed shape for IMC. The way for points and polygons is about the same. With a few from this steps You can also edit the RM vector shapes for own figuration.

Is this Your wish?

fjordfisher

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Curados Project 12 years 5 months ago #736

AnglingCharts Offline	The starting point should probably be creating a lake shape and relevant topography. This would then either 1. Be used as the backdrop for using RM as a realtime logging/plotting facility in the boat 2. Be used in combination with depth logs in RM from collected historical data. Trevor
	http://www.anglingcharts.com/ Mucking about in boats The administrator has disabled public write access.