Roman Prism and Grism

.travis.yml

@@ -48,7 +48,7 @@ install:
 
 before_script:
     # Get WebbPSF data files (just a subset of the full 250 MB!) and set up environment variable
-    - wget https://stsci.box.com/shared/static/qcptcokkbx7fgi3c00w2732yezkxzb99.gz -O /tmp/minimal-webbpsf-data.tar.gz
+    - wget https://stsci.box.com/shared/static/ci3vkozwgyj82f1qle986k1hmeoggzzh.gz -O /tmp/minimal-webbpsf-data.tar.gz
     - tar -xzvf /tmp/minimal-webbpsf-data.tar.gz
     - export WEBBPSF_PATH="${TRAVIS_BUILD_DIR}/webbpsf-data"
 

webbpsf/roman.py

@@ -11,15 +11,21 @@
 import os.path
 import poppy
 import numpy as np
-from . import webbpsf_core
-from scipy.interpolate import griddata
+
+from scipy.interpolate import griddata, RegularGridInterpolator
 from astropy.io import fits
 import astropy.units as u
 import logging
 
+from . import webbpsf_core
+from .optics import _fix_zgrid_NaNs
+
+
 _log = logging.getLogger('webbpsf')
 import pprint
 
+GRISM_FILTER = 'G150'
+PRISM_FILTER = 'P120'
 
 class WavelengthDependenceInterpolator(object):
     """WavelengthDependenceInterpolator can be configured with
@@ -158,16 +164,46 @@ def get_aberration_terms(self, wavelength):
             assert len(aberration_array.shape) == 2, "computed aberration array is not 2D " \
                                                      "(inconsistent number of Zernike terms " \
                                                      "at each point?)"
-
-            field_position = tuple(np.clip(self.field_position, 4, 4092))
+            field_position = tuple(self.field_position)
             coefficients = griddata(
                 np.asarray(field_points),
                 np.asarray(aberration_terms),
                 field_position,
                 method='linear'
             )
             if np.any(np.isnan(coefficients)):
-                raise RuntimeError("Could not get aberrations for input field point")
+                # FIND TWO CLOSEST INPUT GRID POINTS:
+                dist = []
+                corners = field_points[1:]  # use only the corner points
+                for i, ip in enumerate(corners):
+                    dist.append(np.sqrt(((ip[0] - field_position[0]) ** 2) + ((ip[1] - field_position[1]) ** 2)))
+                min_dist_indx = np.argsort(dist)[:2]  # keep two closest points
+                # DEFINE LINE B/W TWO POINTS, FIND ORTHOGONAL LINE AT POINT OF INTEREST,
+                # AND FIND INTERSECTION OF THESE TWO LINES.
+                x1, y1 = corners[min_dist_indx[0]]
+                x2, y2 = corners[min_dist_indx[1]]
+                dx = x2 - x1
+                dy = y2 - y1
+                a = (dy * (field_position[1] - y1) + dx * (field_position[0] - x1)) / (dx * dx + dy * dy)
+                closest_interp_point = (x1 + a * dx, y1 + a * dy)
+                # INTERPOLATE ABERRATIONS TO CLOSEST INTERPOLATED POINT:
+                coefficients = griddata(
+                    np.asarray(field_points),
+                    np.asarray(aberration_terms),
+                    closest_interp_point,
+                    method='linear')
+                # IF CLOSEST INTERPOLATED POINT IS STILL OUTSIDE THE INPUT GRID,
+                # THEN USE NEAREST GRID POINT INSTEAD:
+                if np.any(np.isnan(coefficients)):
+                    coefficients = aberration_terms[min_dist_indx[0] + 1]
+                    _log.warn("Attempted to get aberrations at field point {} which is outside the range "
+                              "of the reference data; approximating to nearest input grid point".format(field_position))
+                else:
+                    _log.warn("Attempted to get aberrations at field point {} which is outside the range "
+                              "of the reference data; approximating to nearest interpolated point {}".format(
+                        field_position, closest_interp_point))
+                assert not np.any(np.isnan(coefficients)), "Could not compute aberration " \
+                                                           "at field point {}".format(field_position)
         if self._omit_piston_tip_tilt:
             _log.debug("Omitting piston/tip/tilt")
             coefficients[:3] = 0.0  # omit piston, tip, and tilt Zernikes
@@ -302,7 +338,7 @@ def __init__(self):
         self._masked_pupil_path = None
 
         # List of filters that need the masked pupil
-        self._masked_filters = ['F184']
+        self._masked_filters = ['F184', GRISM_FILTER]
 
         # Flag to en-/disable automatic selection of the appropriate pupil_mask
         self.auto_pupil = True
@@ -459,12 +495,6 @@ class WFI(RomanInstrument):
     def __init__(self):
         """
         Initiate WFI
-
-        Parameters
-        -----------
-        set_pupil_mask_on : bool or None
-            Set to True or False to force using or not using the cold pupil mask,
-            or to None for the automatic behavior.
         """
         # pixel scale is from Roman-AFTA SDT report final version (p. 91)
         # https://roman.ipac.caltech.edu/sims/Param_db.html
@@ -473,22 +503,54 @@ def __init__(self):
         # Initialize the pupil controller
         self._pupil_controller = WFIPupilController()
 
+        # Initialize the aberrations for super().__init__
+        self._aberrations_files = {}
+        self._is_custom_aberrations = False
+        self._current_aberrations_file = ""
+
         super(WFI, self).__init__("WFI", pixelscale=pixelscale)
 
         self._pupil_controller.set_base_path(self._datapath)
 
         self.pupil_mask_list = self._pupil_controller.pupil_mask_list
 
+        # Define defualt aberration files for WFI modes
+        self._aberrations_files = {
+            'imaging': os.path.join(self._datapath, 'wim_zernikes_cycle8.csv'),
+            'prism': os.path.join(self._datapath, 'wim_zernikes_cycle8_prism.csv'),
+            'grism': os.path.join(self._datapath, 'wim_zernikes_cycle8_grism.csv'),
+            'custom': None,
+        }
+
+        # Load default detector from aberration file
         self._detector_npixels = 4096
-        self._detectors = _load_wfi_detector_aberrations(os.path.join(self._datapath, 'wim_zernikes_cycle8.csv'))
-        assert len(self._detectors.keys()) > 0
+        self._load_detector_aberrations(self._aberrations_files[self.mode])
         self.detector = 'SCA01'
 
         self.opd_list = [
             os.path.join(self._WebbPSF_basepath, 'upscaled_HST_OPD.fits'),
         ]
         self.pupilopd = self.opd_list[-1]
 
+    def _load_detector_aberrations(self, path):
+        """
+        Helper function that, given a path to a file containing detector aberrations, loads the Zernike values and
+        populates the class' dictator list with `FieldDependentAberration` detectors. This function achieves this by
+        calling the `webbpsf.roman._load_wfi_detector_aberrations` function.
+
+        Users should use the `override_aberrations` function to override current aberrations.
+
+        Parameters
+        ----------
+        path : string
+            Path to file containing detector aberrations
+        """
+        detectors = _load_wfi_detector_aberrations(path)
+        assert len(detectors.keys()) > 0
+
+        self._detectors = detectors
+        self._current_aberrations_file = path
+
     def _validate_config(self, **kwargs):
         """Validates that the WFI is configured sensibly
 
@@ -520,21 +582,13 @@ def pupil(self, value):
     def pupil_mask(self):
         return self._pupil_controller.pupil_mask
 
-    @RomanInstrument.filter.setter
-    def filter(self, value):
-        value = value.upper()  # force to uppercase
-        if value not in self.filter_list:
-            raise ValueError("Instrument %s doesn't have a filter called %s." % (self.name, value))
-        self._filter = value
-        self._pupil_controller.validate_pupil(self.filter)
-
     @pupil_mask.setter
     def pupil_mask(self, name):
         """
         Set the pupil mask
 
         Parameters
-        ------------
+        ----------
         name : string
             Name of setting.
             Settings:
@@ -558,6 +612,124 @@ def _unmasked_pupil_path(self):
     def _masked_pupil_path(self):
         return self._pupil_controller._masked_pupil_path
 
+    def _get_filter_mode(self, wfi_filter):
+        """
+        Given a filter name, return the WFI mode
+
+        Parameters
+        ----------
+        wfi_filter : string
+            Name of WFI filter
+
+        Returns
+        -------
+        mode : string
+            Returns 'imaging', 'grism' or 'prism' depending on filter.
+
+        Raises
+        ------
+        ValueError
+            If the input filter is not found in the WFI filter list
+        """
+
+        wfi_filter = wfi_filter.upper()
+        if wfi_filter == GRISM_FILTER:
+            return 'grism'
+        elif wfi_filter == PRISM_FILTER:
+            return 'prism'
+        elif wfi_filter in self.filter_list:
+            return 'imaging'
+        else:
+            raise ValueError("Instrument %s doesn't have a filter called %s." % (self.name, wfi_filter))
+
+    @property
+    def mode(self):
+        """Current WFI mode"""
+        return self._get_filter_mode(self.filter)
+
+    @mode.setter
+    def mode(self, value):
+        """Mode is set by changing filters"""
+        raise AttributeError("WFI mode cannot be directly specified; WFI mode is set by changing filters.")
+
+    def override_aberrations(self, aberrations_path):
+        """
+        This function loads user provided aberrations from a file and locks this instrument
+        to only use the provided aberrations (even if the filter or mode change).
+        To release the lock and load the default aberrations, use the `reset_override_aberrations` function.
+        To load new user provided aberrations, simply call this function with the new path.
+
+        To load custom aberrations, please provide a csv file containing the detector names,
+        field point positions and Zernike values. The file should contain the following column names/values
+        (comments in parentheses should not be included):
+            - sca (Detector number)
+            - wavelength (µm)
+            - field_point (filed point number/id for SCA and wavelength, starts with 1)
+            - local_x (mm, local detector coords)
+            - local_y (mm, local detector coords)
+            - global_x (mm, global instrument coords)
+            - global_y (mm, global instrument coords)
+            - axis_local_angle_x (XAN)
+            - axis_local_angle_y (YAN)
+            - wfe_rms_waves (nm)
+            - wfe_pv_waves (waves)
+            - Z1 (Zernike phase NOLL coefficients)
+            - Z2 (Zernike phase NOLL coefficients)
+            - Z3 (Zernike phase NOLL coefficients)
+            - Z4 (Zernike phase NOLL coefficients)
+              .
+              .
+              .
+
+        Please refer to the default aberrations files for examples. If you have the WebbPSF data installed and defined,
+        you can get the path to that file by running the following:
+            >>> from webbpsf import roman
+            >>> wfi = roman.WFI()
+            >>> print(wfi._aberrations_files["imaging"])
+
+        Warning: You should not edit the default files!
+        """
+        self._load_detector_aberrations(aberrations_path)
+        self._aberrations_files['custom'] = aberrations_path
+        self._is_custom_aberrations = True
+
+    def reset_override_aberrations(self):
+         """Release detector aberrations override and load defaults"""
+         aberrations_path = self._aberrations_files[self.mode]
+         self._load_detector_aberrations(aberrations_path)
+         self._aberrations_files['custom'] = None
+         self._is_custom_aberrations = False
+
+    @RomanInstrument.filter.setter
+    def filter(self, value):
+
+        # Update Filter
+        # -------------
+        value = value.upper()  # force to uppercase
+
+        if value not in self.filter_list:
+            raise ValueError("Instrument %s doesn't have a filter called %s." % (self.name, value))
+
+        self._filter = value
+
+        # Update Aberrations
+        # ------------------
+        # Check if _aberrations_files has been initiated (not empty) and if aberrations are locked by user
+        if self._aberrations_files and not self._is_custom_aberrations:
+
+            # Identify aberrations file for new mode
+            mode = self._get_filter_mode(self._filter)
+            aberrations_file = self._aberrations_files[mode]
+
+            # If aberrations are not already loaded for the new mode,
+            # load and replace detectors using the new mode's aberrations file.
+            if not os.path.samefile(self._current_aberrations_file, aberrations_file):
+                self._load_detector_aberrations(aberrations_file)
+
+        # Update Pupil
+        # ------------
+        self._pupil_controller.validate_pupil(self._filter)
+
 
 class CGI(RomanInstrument):
     """

webbpsf/tests/test_roman.py

@@ -1,8 +1,12 @@
 import os
+import numpy as np
 import pytest
 from webbpsf import roman, measure_fwhm
 from numpy import allclose
 
+
+GRISM_FILTER = roman.GRISM_FILTER
+PRISM_FILTER = roman.PRISM_FILTER
 MASKED_FLAG = "FULL_MASK"
 UNMASKED_FLAG = "RIM_MASK"
 AUTO_FLAG = "AUTO"
@@ -190,8 +194,51 @@ def _test_filter_pupil(filter_name, expected_pupil):
     _test_filter_pupil('F062', wfi._unmasked_pupil_path)
     _test_filter_pupil('F158', wfi._unmasked_pupil_path)
     _test_filter_pupil('F146', wfi._unmasked_pupil_path)
+    _test_filter_pupil(PRISM_FILTER, wfi._unmasked_pupil_path)
 
     _test_filter_pupil('F184', wfi._masked_pupil_path)
+    _test_filter_pupil(GRISM_FILTER, wfi._masked_pupil_path)
+
+def test_swapping_modes(wfi=None):
+
+    if wfi is None:
+        wfi = roman.WFI()
+
+    tests = [
+        # [filter, mode, pupil_file]
+        ['F062', 'imaging',  wfi._unmasked_pupil_path],
+        ['F184', 'imaging', wfi._masked_pupil_path],
+        [PRISM_FILTER, 'prism', wfi._unmasked_pupil_path],
+        [GRISM_FILTER, 'grism', wfi._masked_pupil_path],
+    ]
+
+    for test_filter, test_mode, test_pupil in tests:
+        wfi.filter = test_filter
+        assert wfi.filter == test_filter
+        assert wfi.mode == test_mode
+        assert wfi._current_aberrations_file == wfi._aberrations_files[test_mode]
+        assert wfi.pupil == test_pupil
+
+def test_custom_aberrations():
+
+    wfi = roman.WFI()
+
+    # Use grism aberrations_file for testing
+    test_aberrations_file = wfi._aberrations_files['grism']
+
+    # Test override
+    # -------------
+    wfi.override_aberrations(test_aberrations_file)
+
+    for filter in wfi.filter_list:
+        wfi.filter = filter
+        assert wfi._current_aberrations_file == test_aberrations_file, "Filter change caused override to fail"
+
+    # Test Release Override
+    # ---------------------
+    wfi.reset_override_aberrations()
+    assert wfi._aberrations_files['custom'] is None, "Custom aberrations file not deleted on override release."
+    test_swapping_modes(wfi)
 
 def test_WFI_limits_interpolation_range():
     wfi = roman.WFI()
@@ -236,6 +283,20 @@ def test_WFI_limits_interpolation_range():
         "Aberration outside wavelength range did not return closest value."
     )
 
+    # Test border pixels that are outside of the ref data
+    # As of cycle 8 and 9, (4, 4) is the first pixel so we
+    # check if (0, 0) is approximated to (4, 4) via nearest point
+    # approximation:
+
+    det.field_position = (0, 0)
+    coefficients_outlier = det.get_aberration_terms(1e-6)
+
+    det.field_position = (4, 4)
+    coefficients_data = det.get_aberration_terms(1e-6)
+
+    assert np.allclose(coefficients_outlier, coefficients_data), "nearest point extrapolation " \
+                                                                 "failed for outlier field point"
+
 def test_CGI_detector_position():
     """ Test existence of the CGI detector position etc, and that you can't set it."""
     cgi = roman.CGI()