Dips and strikes? Dip and strike readings are simple but important geological measurements which can be used for structural and stratigraphic analysis. They are generally made by a field geologist directly at a geological outcrop. The dip of the geological layer is defined as the maximum inclination, in degrees, of the layer from the horizontal…
Read detailsAs geoscientists, we need to bring into ArcGIS various types of gridded data, including surfaces with elevation values, sub-surface horizons with depth values, or imagery with spectral values. If you don’t have access to a dedicated ArcGIS extension for loading such data types, like our own Data Assistant, then the way to load these into ArcGIS…
Read detailsIncrease mapping productivity using Data Driven Pages If you want to create a PDF map book or a map series covering a study area, you can do so with minimum fuss by using Data Driven Pages (DDP). The only thing you need to accomplish this is a polygon layer with a column which contains unique…
Read detailsMake a geodetic New Year’s resolution: stop making basic positioning mistakes! This New Year, why not resolve to stop making basic geodetic positioning mistakes in your ArcGIS documents. We’re sure your boss, customers and organisation will thank you. To help you with this, Exprodat and Priemere GeoTechnology have collaborated to create a free tool, called the Geodetic…
Read detailsUsing a Raster Catalog in ArcCatalog You can use a Raster Catalog to store high volumes of imagery. You can create them from the File menu in ArcCatalog, or from the Create Raster Catalog tool in ArcToolbox. When set up and populated, with some image tiles selected, it will look something like the image below: Using the…
Read detailsThe International Association of Oil and Gas Producers (OGP) recently released EPSG Area Polygons as a freely available spatial dataset that accurately defines the applicable extent of the CRSs and transformations in the EPSG Geodetic Parameter Dataset (EPSG Dataset). However, use of the Area Polygons dataset is not as straightforward as it could be, as…
Read detailsTool parameters are used to set values for elements within a script, allowing you to pick from a drop-down list or navigate to a location without having to edit any script code. Embellishing from my previous blog on listing files in a folder using Python, this blog shows you how to create a script that…
Read detailsThis year two teams from Exprodat decided to enter the Oxfam Trailwalker 2012 event. We thought it would be fun to develop a map-based application to track the positions of our teams and devised a system whereby the walkers would carry smartphones containing built-in GPS receivers for gathering position information. This information would then be…
Read detailsMost geologists like a nice geological block diagram and it is relatively easy to create one for presentations using a combination of GIS and a graphics application. I last created one way back in college (16 years ago!) using a combination of PCI satellite image processing software and CorelDRAW (a popular graphics application). So I…
Read detailsRaster data like digital elevation models (e.g. SRTM), bathymetry (e.g. GEBCO), and gravity (e.g. Sandwell and Smith) can provide valuable context to an area. Since only so much subsurface analysis and interpretation can be done in GIS, getting these rasters into other applications, like GeoFrame, Petrel and Petromod, is important to give wider context to seismic, well and…
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