# DC-2d forward with only 'Dipole-Dipole' or 'pole-dipole' or 'dipole-pole' or 'pole-pole'? **URL:** \ **Category:** DC and IP\ **Created:** [August 19, 2021, 7:06am UTC](https://simpeg.discourse.group/t/dc-2d-forward-with-only-dipole-dipole-or-pole-dipole-or-dipole-pole-or-pole-pole/250 "2021-08-19T07:06:21Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![lp081516](https://avatars.discourse-cdn.com/v4/letter/l/a8b319/32.png) [@lp081516](https://simpeg.discourse.group/u/lp081516)\ **Post date:** [August 19, 2021, 7:06am UTC](https://simpeg.discourse.group/t/dc-2d-forward-with-only-dipole-dipole-or-pole-dipole-or-dipole-pole-or-pole-pole/250/1 "2021-08-19T07:06:21Z")
I found that when I created a survey using simpeg for two-dimensional forward modeling,survey\_type contains just four types of devices(Dipole-Dipole’ or ‘pole-dipole’ or ‘dipole-pole’ or ‘pole-pole’).I was wondering if we could do other types of devices such as Wenner device or others. Here are the comments in the code: def generate\_dcip\_sources\_line( survey\_type, data\_type, dimension\_type, end\_points, topo, num\_rx\_per\_src, station\_spacing, ): “”" Input: \<\<:param str survey\_type: ‘dipole-dipole’ | ‘pole-dipole’ | ‘dipole-pole’ | ‘pole-pole’\>\> ---
**Author:** ![sgkang09](https://yyz2.discourse-cdn.com/free1/user_avatar/simpeg.discourse.group/sgkang09/32/8_2.png) [@sgkang09](https://simpeg.discourse.group/u/sgkang09)\ **Post date:** [August 20, 2021, 4:30pm UTC](https://simpeg.discourse.group/t/dc-2d-forward-with-only-dipole-dipole-or-pole-dipole-or-dipole-pole-or-pole-pole/250/2 "2021-08-20T16:30:57Z")
dipoe-dipole can handle wenner and other types that you mentioned. it literally means the four electrode system rather than typical dipole dipole array. ---
**Author:** ![thibaut.astic](https://yyz2.discourse-cdn.com/free1/user_avatar/simpeg.discourse.group/thibaut.astic/32/109_2.png) [@thibaut.astic](https://simpeg.discourse.group/u/thibaut.astic)\ **Post date:** [August 20, 2021, 5:44pm UTC](https://simpeg.discourse.group/t/dc-2d-forward-with-only-dipole-dipole-or-pole-dipole-or-dipole-pole-or-pole-pole/250/3 "2021-08-20T17:44:30Z")
To add to Seogi’s answer: Yes, SimPEG can forward and invert any type of electrodes configuration. However, the util to generate synthetic surveys you are mentioning indeed is limited in what it can create. The best way for you then to create any type of surveys is to use the I/O utils. This means start from a text file (either with a list of ABMN locations or in a UBC format) and load it using the adequate utils. You will find more examples in the documentation, for example: - from a ABMN file: [Reading and Plotting data with DC.IO class — SimPEG 0.15.0 documentation](http://docs.simpeg.xyz/content/examples/04-dcip/plot_read_DC_data_with_IO_class.html?highlight=abmn) - from a UBC formatted file: [2.5D DC Resistivity and IP Least-Squares Inversion — SimPEG 0.15.0 documentation](http://docs.simpeg.xyz/content/tutorials/06-ip/plot_inv_2_dcip2d.html?highlight=read_dc) ---
**Author:** ![lp081516](https://avatars.discourse-cdn.com/v4/letter/l/a8b319/32.png) [@lp081516](https://simpeg.discourse.group/u/lp081516)\ **Post date:** [September 23, 2021, 2:56am UTC](https://simpeg.discourse.group/t/dc-2d-forward-with-only-dipole-dipole-or-pole-dipole-or-dipole-pole-or-pole-pole/250/4 "2021-09-23T02:56:01Z")
Thank you for your patient answer. In addition, I noticed that direct current forward modeling is based on the survey of a certain device (such as dipole-dipole). According to the theory of finite element, we can obtain the potential of all underground grid nodes by point source.I want to learn more about how Simpeg does this. ---
**Author:** ![zhongmin](https://avatars.discourse-cdn.com/v4/letter/z/74df32/32.png) [@zhongmin](https://simpeg.discourse.group/u/zhongmin)\ **Post date:** [October 12, 2021, 8:21am UTC](https://simpeg.discourse.group/t/dc-2d-forward-with-only-dipole-dipole-or-pole-dipole-or-dipole-pole-or-pole-pole/250/5 "2021-10-12T08:21:14Z")
I have know how to define a survey form a ABMN file now. I have one more question , when I use the IO.from\_abmn\_locations\_to\_survey to build a dc\_survey,I need to assign the data\_dc\_type,if I assign the datatype to “apparent\_resistivity”, how can I generate a “dc\_data” form the Simpeg.data using this dc\_survey? if I solve the problem using simulation, what is the output of dpred , the dpred is apparent\_resistivity or nomalized voltage? ---
**Author:** ![peterfen-eng](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@peterfen-eng](https://simpeg.discourse.group/u/peterfen-eng)\ **Post date:** [May 15, 2022, 12:58pm UTC](https://simpeg.discourse.group/t/dc-2d-forward-with-only-dipole-dipole-or-pole-dipole-or-dipole-pole-or-pole-pole/250/6 "2022-05-15T12:58:07Z")
Ah, only I don’t know how to change the dipole-pole to a symmetrical quadrupole ---
**Author:** ![peterfen-eng](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@peterfen-eng](https://simpeg.discourse.group/u/peterfen-eng)\ **Post date:** [May 15, 2022, 1:01pm UTC](https://simpeg.discourse.group/t/dc-2d-forward-with-only-dipole-dipole-or-pole-dipole-or-dipole-pole-or-pole-pole/250/7 "2022-05-15T13:01:31Z")
I want to do symmetric quadrupoles, I tried to set the position of ABMN, but it did not work properly, it was modified on the basis of dipole