topic Geology in ArcGIS Enterprise Questions

Geology

alexandernongkhlaw — Sat, 15 Jun 2019 17:37:09 GMT

I really need help on this..... I have dip amount value but i don not have strike value... How do i get the strike value using arcgis since i have a raw data map showing only of dip amount.. Please i really need help.. Thank you

Re: Geology

LanceCole — Sat, 15 Jun 2019 18:36:33 GMT

Hi Alexander

Do you have a sample of the data you are working with? Unusual data would contain the dip without the strike. I assume the data is in point format, is there a rotation value for the points that may correspond to the strike?

Re: Geology

alexandernongkhlaw — Sat, 15 Jun 2019 19:23:07 GMT

Like i said i have a raw data.... Showing only the dip value...

Re: Geology

alexandernongkhlaw — Sat, 15 Jun 2019 19:40:56 GMT

Re: Geology

LanceCole — Sat, 15 Jun 2019 21:04:33 GMT

Alexander,

So by raw data you mean you only have a scanned or hard copy of the map? No GIS digital data points, correct?

As you know but for others, the strike is the orientation or rotation of the symbol on the map the dip is a number listed next to the symbol indicating the steepest angle of plunge. On a map oriented with north up, a strike and dip symbol oriented straight up and down the page, the strike would be 0 or 180 depending upon the side of the dip. A strike dip symbol oriented straight across the page would be 90 or 270 depending upon the side of the dip if using azimuths. I would recommend georeferencing your map into ArcGIS as you have coordinates for the corners. Once georeferenced, add a strike and dip symbol for each point on the map then rotate the symbol to align to the symbol on the map. You can also add the dip info as an attribute. The orientation of the symbol can be extracted from the data and populated as an attribute. Sorry but no automatic way to complete this but there are not that many points on the map you attached.

Here a few links for georeferencing and symbol rotation:

Fundamentals of georeferencing a raster dataset

Rotating point feature symbols

Re: Geology

alexandernongkhlaw — Sun, 16 Jun 2019 06:00:41 GMT

Ok got it... But how will i know the value of strike... Cause i need to enter in the attribute table...

Re: Geology

LanceCole — Sun, 16 Jun 2019 12:42:25 GMT

Alexander,

When you create your strike and dip feature class you can set the Strike attribute to control or be populated by the rotation of the strike and dip symbol. Please see How To: Rotate point marker symbols in ArcMap. You can physically rotate the symbol to change the attribute or change the numeric value manually. I hope that helps.

Re: Geology

alexandernongkhlaw — Mon, 17 Jun 2019 08:22:44 GMT

i wish its that simple its confusing...:(

Re: Geology

LanceCole — Mon, 17 Jun 2019 11:32:58 GMT

@Alexander,

It may have been less confusing if I had pasted the correct hyperlink for rotating point marker symbols. See revised link in previous post. My apologies

Here is a video link to Plotting Dip and Strike Readings with ArcGIS. You will need to create the feature class for your strike & dip symbols, add the points and input the data for strike and dip.

Re: Geology

alexandernongkhlaw — Mon, 17 Jun 2019 11:38:45 GMT

10.6.1 hat if i use COGO tool is it of good example.....it'll be helpful if i can see an example of it on how to do..

Re: Geology

alexandernongkhlaw — Mon, 17 Jun 2019 12:14:45 GMT

Lance like i said the video is good but i do not have strike value since i have only dip amount and the raw image...thats why i need to find the strike value of it...but in the video its showing that they already have the strike value

Re: Geology

LanceCole — Mon, 17 Jun 2019 12:33:05 GMT

Alexander,‌

You will need to create a empty feature class or shapefile with the needed attributes and input these yourself.

Create a shapefile or feature class as points with empty Strike and Dip attribute numeric columns. Set the default values to 0 (zero) for these to fields.
Set up the feature symbology and labeling as noted in the video for this new feature. There will not be any points to start.
Georeference the TIF of your map so you can use it in ArcGIS.
Zoom to one of the Strike & Dip symbols on the map in ArcGIS.
Drop a new strike & dip point at the location of the symbol on the map.
Type in the Dip value for the point.
Using the rotate tool rotate the point symbol to line up with the symbol on the map. You can also manually input the rotation value and adjust to best fit using trial and error.
Repeat for the next symbol.

Re: Geology

alexandernongkhlaw — Mon, 17 Jun 2019 12:42:07 GMT

will i get the strike value??

Re: Geology

LanceCole — Mon, 17 Jun 2019 13:41:48 GMT

Alexander,

Yes, if you set this up as noted above the strike field will contain the rotation of the symbol from north in azimuth degrees. You would need to apply the right-hand rule to convert the azimuth strike value to quadrant values if needed. For example, an azimuth of 30 and dipping 15 degrees to the SW would be N30E, 15SW. It has been so long since I worked with Strike and Dip I do not remember all the rules to give other examples.

Re: Geology

alexandernongkhlaw — Tue, 18 Jun 2019 07:34:20 GMT

after georeferencing it came like this..as u can see in the picture is not align with the symbol in the map...i also when to the tab advanced then roataion..arithmetic for the drop down i use the dip amount and this came up

Re: Geology

alexandernongkhlaw — Tue, 18 Jun 2019 07:48:11 GMT

i trued the roation tool also from 35 dip amount it changes to 169.637027412952 at the dip field

Re: Geology

LanceCole — Tue, 18 Jun 2019 11:26:13 GMT

Alexander,

You are are getting there. 1) you should be linking the rotation of the symbol to the Strike field not the Dip field. 2) if ArcGIS renders the this symbol along the long axis, for the symbol you have shown, you should have about 170 input for the strike. I will look at this on my system as soon as I get a chance. 3) you may also need to correct for magnetic declination for the area this map is collected as strike is magnetic north.

Re: Geology

alexandernongkhlaw — Tue, 18 Jun 2019 11:30:52 GMT

1) I have no value for the strike field.

2) & 3) no idea how to do this:)

Re: Geology

LanceCole — Tue, 18 Jun 2019 12:53:09 GMT

Alexander,

You do have Strike values. The long line of the strike dip symbol on your map is oriented along the strike direction. The number is just not printed on the map.

1) Go back to your symbology settings and set the "Rotate Points by Angle in this field" to Strike. Yes, you have all "0" values initially.

2) Next go to the symbol you have shown above and rotate it so it lines up with the one on the map. The strike value should change to something around 170. This is your Strike in degrees azimuth. FYI, you should only need to set the Strike and Dip fields to integer.

3) Add another symbol, rotate, repeat...

You can convert this to quadrant bearings if you would like. For example a azimuth bearing of 170 degrees is equal to S10E. However, strike is normally reported from the north quadrant so it would be reported as N10W. The full strike and dip for this example would be N10W, 35SSW. It is easer just to leave everything in azimuths.

If you want the dip direction simply add 90 degrees to the Strike azimuth bearing. So 170+90=260 degrees for the dip direction or South Southwest (SSW).

Pertaining to the correction for magnetic declination. Looking at the map legend again, it looks like everything is referenced to geographic north not magnetic, so you should be good to go.

Re: Geology

alexandernongkhlaw — Tue, 18 Jun 2019 13:25:29 GMT

i tried according of what you ask me to do its working but i dont know whether is correct or not as i need clarification...first of all if i roatoate it i can roatae right from any direction there wont be any problem right..secondly how to i convert to quadrant bearings