Tipper#
This object can be used to store tipper (ZTEM) surveys - a natural-source geophysical method. Data are provided in the frequency-domain as point source measurements of tipper data.
The following example shows how to generate a tipper survey with associated data stored in geoh5 format and accessible from Geoscience ANALYST.
from pathlib import Path
import numpy as np
from geoh5py.objects import TipperBaseStations, TipperReceivers
from geoh5py.workspace import Workspace
# Create a new project
h5file = Path("my_project.geoh5")
workspace = Workspace(h5file) if h5file.exists() else Workspace.create(h5file)
# Define the pole locations
n_stations = 64
n_lines = 2
x_loc, y_loc = np.meshgrid(
np.linspace(0, 60, n_stations), np.linspace(-20, 20.0, n_lines)
)
vertices = np.c_[x_loc.ravel(), y_loc.ravel(), np.zeros_like(x_loc).ravel()]
# Assign a line ID to the poles (vertices)
parts = np.kron(np.arange(n_lines), np.ones(n_stations)).astype("int")
# Create the survey from vertices
receivers = TipperReceivers.create(workspace, vertices=vertices, parts=parts)
base = TipperBaseStations.create(workspace, vertices=vertices)
We have so far created two seperate entities, one for the receiver locations and another for the base station(s). In order to finalize the survey, the association must be made between the two entities:
receivers.base_station = base
or equivalently
base.receivers = receivers
Only one of the two options above is needed.
Metadata#
Along with the geoh5py.objects.surveys.electromagnetics.tipper.TipperReceivers, the metadata contains all the necessary information to define the geophysical experiment.
receivers.metadata
{'EM Dataset': {'Base stations': UUID('c36e86f3-3db7-4280-8b28-bd15dc0976a1'),
'Channels': [],
'Input type': 'Rx and base stations',
'Property groups': [],
'Receivers': UUID('50afd3e5-e9e6-4a3c-ae41-ca3ce724bdbc'),
'Survey type': 'ZTEM',
'Unit': 'Hertz (Hz)'}}
Channels#
List of frequencies at which the data are provided.
receivers.channels = [30.0, 45.0, 90.0, 180.0, 360.0, 720.0]
Input type#
Generic label used in the geoh5 standard for all EM survey entities. Restricted to Rx and base station in the case of a tipper survey.
Property groups#
List of geoh5py.groups.property_group.PropertyGroup instances defining the various data components (e.g. Txz (real), Tyz (imag), …). It is not required to supply all components of the impedence tensor, but it is expected that each component contains a list of data channels of length and in the same order as the Channels (one Data per frequency).
The class method geoh5py.objects.surveys.electromagnetics.base.BaseEMSurvey.add_components_data() can help users add data from nested dictionaries. Below is an example using four components:
# Arbitrary data generator using sine functions
def data_fun(c, f):
return (c + 1.0) * (f + 1.0) * np.sin(f * np.pi * (x_loc * y_loc).ravel() / 400.0)
# Create a nested dictionary of component and frequency data.
data = {
component: {
f"{component}_{freq}": {"values": data_fun(cc, ff)}
for ff, freq in enumerate(receivers.channels)
}
for cc, component in enumerate(
[
"Txz (real)",
"Txz (imaginary)",
"Tyz (real)",
"Tyz (imaginary)",
]
)
}
receivers.add_components_data(data)
[<geoh5py.groups.property_group.PropertyGroup at 0x7aace0005ee0>,
<geoh5py.groups.property_group.PropertyGroup at 0x7aace00e2660>,
<geoh5py.groups.property_group.PropertyGroup at 0x7aace00e3140>,
<geoh5py.groups.property_group.PropertyGroup at 0x7aace00e3a10>]
Metadata are updated immediately to reflect the addition of components:
receivers.metadata
{'EM Dataset': {'Base stations': UUID('c36e86f3-3db7-4280-8b28-bd15dc0976a1'),
'Channels': [30.0, 45.0, 90.0, 180.0, 360.0, 720.0],
'Input type': 'Rx and base stations',
'Property groups': ['Txz (real)',
'Txz (imaginary)',
'Tyz (real)',
'Tyz (imaginary)'],
'Receivers': UUID('50afd3e5-e9e6-4a3c-ae41-ca3ce724bdbc'),
'Survey type': 'ZTEM',
'Unit': 'Hertz (Hz)'}}
Data channels associated with each component can be quickly accessed through the geoh5py.objects.surveys.electromagnetics.base.BaseEMSurvey.components() property:
receivers.components
{'Txz (real)': [<geoh5py.data.float_data.FloatData at 0x7aace01d4a10>,
<geoh5py.data.float_data.FloatData at 0x7aaceb4655b0>,
<geoh5py.data.float_data.FloatData at 0x7aad083459d0>,
<geoh5py.data.float_data.FloatData at 0x7aaceb602f30>,
<geoh5py.data.float_data.FloatData at 0x7aace853b710>,
<geoh5py.data.float_data.FloatData at 0x7aace0074bc0>],
'Txz (imaginary)': [<geoh5py.data.float_data.FloatData at 0x7aace8507d10>,
<geoh5py.data.float_data.FloatData at 0x7aace00a1f10>,
<geoh5py.data.float_data.FloatData at 0x7aaceb43d820>,
<geoh5py.data.float_data.FloatData at 0x7aaceb43ecf0>,
<geoh5py.data.float_data.FloatData at 0x7aace00e0cb0>,
<geoh5py.data.float_data.FloatData at 0x7aace00e23f0>],
'Tyz (real)': [<geoh5py.data.float_data.FloatData at 0x7aace00a3770>,
<geoh5py.data.float_data.FloatData at 0x7aace00e10d0>,
<geoh5py.data.float_data.FloatData at 0x7aace00e1250>,
<geoh5py.data.float_data.FloatData at 0x7aace00e12e0>,
<geoh5py.data.float_data.FloatData at 0x7aace00e11f0>,
<geoh5py.data.float_data.FloatData at 0x7aace00e0a40>],
'Tyz (imaginary)': [<geoh5py.data.float_data.FloatData at 0x7aace00a2c00>,
<geoh5py.data.float_data.FloatData at 0x7aace00e3d40>,
<geoh5py.data.float_data.FloatData at 0x7aace00e3e00>,
<geoh5py.data.float_data.FloatData at 0x7aace00e3c20>,
<geoh5py.data.float_data.FloatData at 0x7aace00e3ef0>,
<geoh5py.data.float_data.FloatData at 0x7aace00e3860>]}
Receivers#
Generic label used in the geoh5 standard for EM survey to identify the geoh5py.objects.surveys.electromagnetics.tipper.TipperReceivers entity.
Base stations#
Generic label used in the geoh5 standard for EM survey to identify the geoh5py.objects.surveys.electromagnetics.tipper.TipperBaseStations entity.
Survey type#
Label identifier for ZTEM survey type.
Unit#
Units for frequency sampling of the data: Hertz (Hz), KiloHertz (kHz), MegaHertz (MHz) or Gigahertz (GHz).
workspace.finalize()